Tuesday, May 18, 2010
sadharnikaran
Aristotle's model has unrealistic linear approach due to which number of biases created and advancement of the communication discipline stained. But the Sadharanikaran model is non-linear and hence free from the limitations of Aristotle's model.
The scope of the Sadharanikaran model is too broad as compared to Aristotle's model. The latter is considered applicable to public speaking merely. But the former seems applicable for the study of all levels of communication from intrapersonal to interpersonal to mass. Its scope ranges even from the human communication to the attainment of Moksha. Thus it is in consonance with the Hindu worldview.
In Aristotle's model, the receiver is vulnerable to dominance and manipulation by the sender as he/she is passive. In the Sadharanikaran model, though the relationship is hierarchical the sender and the receiver are Sahridayas and thus are capable of experiencing satisfaction and joy. This model offers explanation of how successful communication is possible in Hindu society where complex hierarchies of castes, languages, cultures and religious practices are prevalent.
Finally, these two models differ vastly while setting the goal of communication. Aristotle's model has a highly specific and narrower goal of influencing or persuading the receiver as intended by the sender. The Sadharanikaran model, on the other hand, aims mutual understanding and becoming Sahridaya. Its goal covers worldly as well as spiritual achievements by encompassing all of Artha, Kama, Dharma and Moksha.
By this comparative understanding, we come to the conclusion that Aristotle's model cannot represent and describe the communication theory and practice of countries like Nepal and India.
The scope of the Sadharanikaran model should be properly understood. With vast diversities of cultures and philosophies within the Hindu society, it is just one of many models that could be developed. Many theories and models of communication would come out if communication discipline has enthusiasm of encountering with different Hindu philosophical traditions.
Sunday, May 16, 2010
theorys of communication
There are three main paradigms in media effects: hypodermic needle (i.e., direct, or strong effects), limited effects, and the powerful to limited effects. "Uses and Gratifications" falls under the second paradigm which reached its apex around 1940-1960, when studies helped realize that the first paradigm was inaccurate.
basic modle
The Uses and Gratifications Theory follows a basic model. It is an audience-centered approach. When an audience actively seeks out media, they are typically seeking it in order to gratify a need. For example, in social situations, people may feel more confident and knowledgeable when they have specific facts and stories from media to add to conversation. By seeking out media, a person fulfills a need to be informed.
Social situations and psychological characteristics motivate the need for media, which motivates certain expectations of that media. This expectation leads one to be exposed to media that would seemingly fit expectations, leading to an ultimate gratification.
The media dependency theory, has also been explored as an extension to the uses and gratifications approach to media, though there is a subtle difference between the two theories. People's dependency on media proves audience goals to be the origin of the dependency while the uses and gratifications approach focuses more on audience needs (Grant et al., 1998). Still, both theories agree that media use can lead to media dependency(Rubin, 1982).
The media dependency theory states that the more dependent an individual is on the media for to fulfill needs, the more significant the media becomes to that person. DeFleur and Ball-Rokeach (1976) illustrate dependency as the relationship between media content, the nature of society, and the behavior of audiences. Littlejohn (2002) also explained that people will become more dependent on media that meet a number of their needs than on media that touch only a few ones. Dependency on a certain medium is influenced by the number sources open to an individual. Individuals are usually more dependent on available media if their access to media alternatives is limited. The more alternatives there are for an individual, the lesser is the dependency on and influence of a specific medium.
The hypodermic needle model claims that consumers are strongly affected by media and have no say in how the media influences them. The main idea of the Uses and Gratifications model is that people are not helpless victims of all-powerful media, but use media to fulfill their various needs. These needs serve as motivations for using media.
Historical Development
Beginning in the 1940s, researchers began seeing patterns under the perspective of the uses and gratifications theory in radio listeners [1] Early research was concerned with topics such as children's use of comics and the absence of newspapers during a newspaper strike (Infante, Rancer, and Womack).[2][citation needed]). An interest in more psychological interpretations also emerged during this time [3] In 1974, Katz, Blumler and Gurevitch [4] realized that most Uses and Gratification studies were most concerned with: 1. The social and psychological origins of 2. needs which generate 3. expectations 4. of mass media or other sources, which lead to 5. differential patterns of media exposure (or engagement in other activities), resulting in 6. need gratifications and 7. other consequences, perhaps mostly unintended ones [5] Blumler made some interesting points why Uses and Gratifications cannot measure an active audience. "The issue to be considered here is whether what has been thought about Uses and Gratifications Theory has been an article of faith and if it could now be converted into an empirical question such as: How to measure an active audience?" (Blumler, 1979).
It has not been done for these reasons. The notion of active audience has conflated an extraordinary range of meanings, including utility, intentionality, selectivity and imperviousness to influence.
Utility—Mass communication has uses to people.Intentionality—Media consumption is directed by prior motivation.Selectivity—Media behavior reflects prior interests and preferences.Imperviousness—The lessened ability of media to influence an obstinate audience [6]
In 1948, Lasswell introduced a four-functional interpretation of the media on a macro-sociological level. Media served the functions of surveillance, correlation, entertainment and cultural transmission for both society and individuals [7]
In 1972, Blumler and Brown[citation needed] extended Lasswell's four groups 25 years later. These included four primary factors for which one may use the media:Diversion—Escape from routine and problems; an emotional release.Personal Relationships—Social utility of information in conversation; substitution of media for companionship.Personal Identity or Individual Psychology—Value reinforcement or reassurance; self-understanding, reality exploration.Surveillance—Information about factors which might affect one or will help one do or accomplish something (Severin and Tankard, 1997[citation needed]) [8]
Katz, Gurevitch and Haas (1973) saw the mass media as a means by which individuals connect or disconnect themselves with others. They developed 35 needs taken from the largely speculative literature on the social and psychological functions of the mass media and put them into five categories:
Cognitive needs—Acquiring information, knowledge and understanding.Affective needs—Emotion, pleasure, feelings.Personal integrative needs—Credibility, stability, status.Social integrative needs—Family and friends.Tension release needs—Escape and diversion (Severin and Tankard, 1997).
critisim
Many people have criticized this theory as they believe the public has no control over the media and what it produces. It can also be said to be too kind to the media, as they are being 'let off the hook' and do not need to take responsibility for what they produce.
"The nature of the theory underlying Uses and Gratifications research is not totally clear," (Blumler, 1979) This makes the line between gratification and satisfaction blurred calling into question if we only seek what we desire or actually enjoy it. (Palmgreen,P., and Rayburn,J.D., 1985)
"Practitioners of Uses and Gratifications research have been criticized for a formidable array of shortcomings in their outlook -- they are taxed for being crassly atheoretical, perversely eclectic, ensnared in the pitfalls of functionalism and for flirting with the positions at odds with their functionalist origins," (Blumler, 1979).
The biggest issue for the Uses and Gratifications Theory is its being non-theoretical, being vague in key concepts, and being nothing more than a data-collecting strategy (Littlejohn, 2002; Severin and Tankard, 1997; McQuail 1994).
It seems that using this sociologically-based theory has little to no link to the benefit of psychology due to its weakness in operational definitions and weak analytical mode. Also, it is focused too narrowly on the individual and neglects the social structure and place of the media in that structure (Severin and Tankard, 1997).
Due to the individualistic nature of Uses and Gratification theory, it is difficult to take the information that is collected in studies. Most research relies on pure recollection of memory rather than data. (Katz, 1987). This makes self-reports complicated and immeasurable.
This theory has also been blasted by media hegemony advocates who say it goes too far in claiming that people are free to choose the media fare and the interpretations they want (Severin and Tankard, 1997). Other motives that may drive people to consume media may involve low level attention, a habit or a mildly pleasant stimulation. Uniform effects are not the kind of factor the Uses and Gratifications approach would predict (Severin and Tankard, 1997
agenda-setting theory
The agenda-setting theory is the theory that the mass-news media have a large influence on audiences by their choice of what stories to consider newsworthy and how much prominence and space to give them.[1] Agenda-setting theory’s main postulate is salience transfer. Salience transfer is the ability of the mass media to transfer issues of importance from their mass media agendas to public agendas.
History
[edit] Foundation
The media agenda is the set of issues addressed by media sources and the public agenda which are issues the public consider important.[2] Agenda-setting theory was introduced in 1972 by Maxwell McCombs and Donald Shaw in their ground breaking study of the role of the media in 1968 presidential campaign in Chapel Hill, North Carolina.[3] The theory explains the correlation between the rate at which media cover a story and the extent that people think that this story is important. This correlation has been shown to occur repeatedly.
In the dissatisfaction of the magic bullet theory, McCombs and Shaw introduced agenda-setting theory in the Public Opinion Quarterly.[3] The theory was derived from their study that took place in Chapel Hill, NC, where the researchers surveyed 100 undecided voters during the 1968 presidential campaign on what they thought were key issues and measured that against the actual media content.[3] The ranking of issues was almost identical, and the conclusions matched their hypothesis that the mass media positioned the agenda for public opinion by emphasizing specific topics.[4] Subsequent research on agenda-setting theory provided evidence for the cause-and-effect chain of influence being debated by critics in the field.
One particular study made leaps to prove the cause-effect relationship. The study was conducted by Yale researchers, Shanto Iyengar, Mark Peters, and Donald Kinder. The researchers had three groups of subjects fill out questionnaires about their own concerns and then each group watched different evening news programs, each of which emphasized a different issue. After watching the news for four days, the subjects again filled out questionnaires and the issues that they rated as most important matched the issues they viewed on the evening news.[5] The study demonstrated a cause-and-effect relationship between media agenda and public agenda. Since the theory’s conception, more than 350 studies have been performed to test the theory. The theory has evolved beyond the media's influence on the public's perceptions of issue salience to political candidates and corporate reputation
Functions
The agenda-setting function has multiple components:
Media agenda are issues discussed in the media, such as newspapers, television, and radio.
Public agenda are issues discussed and personally about members of the public.
Policy agenda are issues that policy makers consider important, such as legislators.
Corporate agenda are issues that big business and corporations consider important, including corporations.
These four agendas are interrelated. The two basic assumptions underlie most research on agenda-setting are that the press and the media do not reflect reality, they filter and shape it, and the media concentration on a few issues and subjects leads the public to perceive those issues as more important than other issues.
Diffusion
The media uses diffusion to spread ideas and aid in its agenda setting. Opinion Leaders and boundary spanners are very important to the media at using their networks to pass on the flow of information.
An opinion leader is often someone who is thought of by others to know a significant amount of information on a topic or is an "expert". This could be anyone from a specialist in a certain field, a politician who is the head of a specific congressional committee, or a mom who is very active in the PTA. They are often at the center of a social network, more attentive to outside information and capable of influence. Since the opinion leaders are those in a social network who are most likely to watch the news or pay attention to the media, they are an extremely important tool at spreading information to the masses.
Boundary Spanners are those in a social network who can span across various social networks. They can be essential to the flow of novel information. Boundary spanners can be used by the media in setting its agenda by getting information and ideas to a variety of social networks, rather than just one.
A study showing the effects of diffusion was Project Revere. Sociologists at the University of Washington from 1951 to 1953 would drop leaflets from an airplane onto a town. They then would see how long it would take for the information to pass by word of mouth to those who did not get a leaflet. Their findings showed that children are very effective in the diffusion process, thus proving how easy it is for a child to be affected by the media.
The Accessibility Bias
This is a theory that states that information that can be more easily retrieved from memory dominates our judgments, opinions and decisions. So in simpler terms, when someone hears information repeatedly and frequently, they are more likely to remember it.
S. Iyengar's article titled "The accessibility bias in politics: television news and public opinion" looks at just this theory.
He states that "In the area of public affairs, readily accessible information is more frequently conveyed by the media than information that is less accessible, and is more up to date."
The Accessibility Bias is effective because people are cognitive misers. We have limited resources (such as time) and cannot learn about every single subject there is. We also like to use heuristics or "shortcuts" when it comes to learning about topics that we may not have an interest in or are not particularly educated in. This is why we turn to the media to gain this information. So if the media decides to show a certain topic more often than another it shapes the agenda and shapes what people remember and call back to at a later
[edit] Cognitive Effects Model
Early media effects studies done by Lazarfled and Berelson showed that political campaigns have very little effect on voters, but instead that those closest to them (family and friends) as well as cognitions.
Cognition is a term referring to the mental processes involved in gaining knowledge and comprehension, including thinking, knowing, remembering, judging and problem-solving. These are higher-level functions of the brain and encompass language, imagination, perception and planning. (Defined by Psychology at about.com).
The Cognitive effect model found that the media has an indirect influence on an audiences' attitude. A viewer already has set ideas and opinions, the media cannot do much to change those. However by showing certain stories more often than others and shaping the agenda they can shape what an audience puts importance on.
If the media reports more on the economy than international news then people will have more information on the economy and think that the issue is more important than what else is going on around the world. This does not mean that the media has changed their opinion on either topic, simply changed how much they may think about the particular topic.
Characteristics
Research has focused on characteristics of audience, the issues, and the media that might predict variations in the agenda setting effect.
Research done by Weaver in 1977 suggested that individuals vary on their need for orientation. Need for orientation is a combination of the individual’s interest in the topic and uncertainty about the issue. The higher levels of interest and uncertainty produce higher levels of need for orientation. So the individual would be considerably likely to be influenced by the media stories (psychological aspect of theory).[2]
Research performed by Zucker in 1978 suggested that an issue is obtrusive if most members of the public have had direct contact with it, and less obtrusive if audience members have not had direct experience. This means that agenda setting results should be strongest for unobtrusive issues because audience members must rely on media for information on these topics.[2]
Quote on agenda setting- "The media doesn't tell us what to think; it tells us what to think about"- Bernard C. Cohen (1963
Levels of agenda setting
The first-level agenda setting is most traditionally studied by researchers. In this level the media use objects or issues to influence the public. In this level the media suggest what the public should think about (amount of coverage). In second-level agenda setting, the media focuses on the characteristics of the objects or issues. In this level the media suggest how the people should think about the issue. There are two types of attributes: cognitive (subtantative, or topics) and affective (evaluative, or positive, negative, neutral). Intermedia agenda setting involves salience transfer among the media.Coleman and Banning 2006; Lee 2005; Shoemaker & Reese, 1996
Usage
The theory is used in political advertising, political campaigns and debates, business news and corporate reputation,[6] business influence on federal policy,[7] legal systems, trials,[8] role of groups, audience control, public opinion, and public relations
Strengths and weaknesses of theory
It has explanatory power because it explains why most people prioritize the same issues as important. It also has predictive power because it predicts that if people are exposed to the same media, they will feel the same issues are important. Its meta-theoretical assumptions are balanced on the scientific side and it lays groundwork for further research. Furthermore, it has organizing power because it helps organize existing knowledge of media effects.
There are also limitations, such as media users may not be as ideal as the theory assumes. People may not be well-informed, deeply engaged in public affairs, thoughtful and skeptical. Instead, they may pay only casual and intermittent attention to public affairs and remain ignorant of the details. For people who have made up their minds, the effect is weakened. News media cannot create or conceal problems, they may only alter the awareness, priorities and salience people attached to a set of problems.[citation needed] Research has largely been inconclusive in establishing a causal relationship between public salience and media coverage.[citation needed]
two step flow theory
[edit] History and Orientation
The two-step flow model hypothesizes that ideas flow from mass media to opinion leaders, and from them to a wider population. It was first introduced by Paul Lazarsfeld et al. in 1944[1] and elaborated by Elihu Katz and Lazarsfeld in 1955[2] and subsequent publications.[3] Lowery and DeFleur argue the book was much more than a simple research report: it was an effort to interpret the authors' research within a framework of conceptual schemes, theoretical issues, and research findings drawn broadly from the scientific study of small groups [4] Unlike the hypodermic needle model, which considers mass media effects to be direct, the two-step flow model stresses human agency.
According to Lazarsfeld and Katz, mass media information is channeled to the "masses" through opinion leadership. The people with most access to media, and having a more literate understanding of media content, explain and diffuse the content to others.
Based on the two-step flow hypothesis, the term “personal influence” came to illustrate the process intervening between the media’s direct message and the audience’s reaction to that message. Opinion leaders tend to be similar to those they influence—based on personality, interests, demographics, or socio-economic factors. These leaders tend to influence others to change their attitudes and behaviors. The two-step theory refined the ability to predict how media messages influence audience behavior and explains why certain media campaigns do not alter audiences’ attitudes. This hypothesis provided a basis for the multi-step flow theory of mass communication.[5]
[edit] Criticisms
The original two-step flow hypothesis—that ideas flow from the media to opinion leaders and then to less active sections of the population—has been criticized and negated by myriad consequent studies. Findings from Deutschmann and Danielson assert, “we would urge that the Katz-Lazarsfeld two-stage flow hypothesis, as a description of the initial information process, be applied to mass communication with caution”[6]. They find substantial evidence that initial mass media information flows directly to people on the whole and is not relayed by opinion leaders.
Furthermore, the two-step hypothesis does not adequately describe the flow of learning. Everett Rogers’ “Diffusion of Innovations” cites one study in which two-thirds of respondents accredited their awareness to the mass media rather than face-to-face communication. Similarly, critics argue that most of Lazarsfeld’s findings pertain to learning factors involved with general media habits rather than the learning of particular information. Both findings suggest a greater prevalence of a one-step flow of communication.
However, Lazarsfeld’s two-step hypothesis is an adequate description to understand the media’s influence on belief and behavior. Troldahl finds that media exposure is a first step to introduce discussion, at which point opinion leaders initiate the second-step flow. These findings also realize opinion leaders decisive role in the balance theory, which suggests that people are motivated to keep consistency among their current beliefs and opinions. If a person is exposed to new observations that are inconsistent with present beliefs, he or she is thrown into imbalance. This person will then seek advice from their opinion leader, to provide them with additional cognitions to bring them back into balance.
psychology
english nots
A computer network, often simply referred to as a network, is a collection of computers and devices connected by communications channels that facilitates communications among users and allows users to share resources with other users. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of types and categories and also presents the basic components of a network.
Introduction
A computer network allows sharing of resources and information among devices connected to the network. The Advanced Research Projects Agency (ARPA) funded the design of the Advanced Research Projects Agency Network (ARPANET) for the United States Department of Defense. It was the first operational computer network in the world.[1] Development of the network began in 1969, based on designs developed during the 1960s. For a history see ARPANET, the first network.
Purpose
Facilitating communications. Using a network, people can communicate efficiently and easily via e-mail, instant messaging, chat rooms, telephony, video telephone calls, and videoconferencing.
Sharing hardware. In a networked environment, each computer on a network can access and use hardware on the network. Suppose several personal computers on a network each require the use of a laser printer. If the personal computers and a laser printer are connected to a network, each user can then access the laser printer on the network, as they need it.
Sharing files, data, and information. In a network environment, any authorized user can access data and information stored on other computers on the network. The capability of providing access to data and information on shared storage devices is an important feature of many networks.
Sharing software. Users connected to a network can access application programs on the network
Connection method
Computer networks can be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as optical fiber, Ethernet, Wireless LAN, HomePNA, Power line communication or G.hn.
Ethernet uses physical wiring to connect devices. Frequently deployed devices include hubs, switches, bridges and/or routers. Wireless LAN technology is designed to connect devices without wiring. These devices use radio waves or infrared signals as a transmission medium. ITU-T G.hn technology uses existing home wiring (coaxial cable, phone lines and power lines) to create a high-speed (up to 1 Gigabit/s) local area network.
Wired technologies
Twisted pair wire is the most widely used medium for telecommunication. Twisted-pair wires are ordinary telephone wires which consist of two insulated copper wires twisted into pairs and are used for both voice and data transmission. The use of two wires twisted together helps to reduce crosstalk and electromagnetic induction. The transmission speed ranges from 2 million bits per second to 100 million bits per second.
Coaxial cable is widely used for cable television systems, office buildings, and other worksites for local area networks. The cables consist of copper or aluminum wire wrapped with insulating layer typically of a flexible material with a high dielectric constant, all of which are surrounded by a conductive layer. The layers of insulation help minimize interference and distortion. Transmission speed range from 200 million to more than 500 million bits per second.
Optical fiber cable consists of one or more filaments of glass fiber wrapped in protective layers. It transmits light which can travel over extended distances without signal loss. Fiber-optic cables are not affected by electromagnetic radiation. Transmission speed may reach trillions of bits per second. The transmission speed of fiber optics is hundreds of times faster than for coaxial cables and thousands of times faster than for twisted-pair wire.
Wireless technologies
Terrestrial Microwave – Terrestrial microwaves use Earth-based transmitter and receiver. The equipment look similar to satellite dishes. Terrestrial microwaves use low-gigahertz range, which limits all communications to line-of-sight. Path between relay stations spaced approx. 30 miles apart. Microwave antennas are usually placed on top of buildings, towers, hills, and mountain peaks.
Communications Satellites – The satellites use microwave radio as their telecommunications medium which are not deflected by the Earth's atmosphere. The satellites are stationed in space, typically 22,000 miles (for geosynchronous satellites) above the equator. These Earth-orbiting systems are capable of receiving and relaying voice, data, and TV signals.
Cellular and PCS Systems – Use several radio communications technologies. The systems are divided to different geographic area. Each area has low-power transmitter or radio relay antenna device to relay calls from one area to the next area.
Wireless LANs – Wireless local area network use a high-frequency radio technology similar to digital cellular and a low-frequency radio technology. Wireless LANs use spread spectrum technology to enable communication between multiple devices in a limited area. An example of open-standards wireless radio-wave technology is IEEE 802.11b.
Bluetooth – A short range wireless technology. Operate at approx. 1Mbps with range from 10 to 100 meters. Bluetooth is an open wireless protocol for data exchange over short distances.
The Wireless Web – The wireless web refers to the use of the World Wide Web through equipments like cellular phones, pagers,PDAs, and other portable communications devices. The wireless web service offers anytime/anywhere connection.
Scale
Networks are often classified as local area network (LAN), wide area network (WAN), metropolitan area network (MAN), personal area network (PAN), virtual private network (VPN), campus area network (CAN), storage area network (SAN), and others, depending on their scale, scope and purpose. (e.g., Controller Area Network (CAN)) Usage, trust level, and access right often differ between these types of network. For example, LANs tend to be designed for internal use by an organization's internal systems and employees in individual physical locations (such as a building), while WANs may connect physically separate parts of an organization and may include connections to third parties
Functional relationship (network architecture)
Computer networks may be classified according to the functional relationships which exist among the elements of the network, e.g., active networking, client-server and peer-to-peer (workgroup) architecture
Network topology
Computer networks may be classified according to the network topology upon which the network is based, such as bus network, star network, ring network, mesh network, star-bus network, tree or hierarchical topology network. Network topology is the coordination by which devices in the network are arrange in their logical relations to one another, independent of physical arrangement. Even if networked computers are physically placed in a linear arrangement and are connected to a hub, the network has a star topology, rather than a bus topology. In this regard the visual and operational characteristics of a network are distinct. Networks may be classified based on the method of data used to convey the data, these include digital and analog networks
Personal area network
A personal area network (PAN) is a computer network used for communication among computer and different information technological devices close to one person. Some examples of devices that are used in a PAN are personal computers, printers, fax machines, telephones, PDAs, scanners, and even video game consoles. A PAN may include wired and wireless connections between devices. The reach of a PAN typically extends to 10 meters.[2] Wired PAN network is usually constructed with USB and Firewire while wireless with Bluetooth and Infrared.[3]
Local area network
A local area network (LAN) is a network that connects computers and devices in a limited geographical area such as home, school, computer laboratory, office building, or closely positioned group of buildings. Each computer or device on the network is a node. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-T G.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines)[4].
All interconnected devices must understand the network layer (layer 3), because they are handling multiple subnets (the different colors). Those inside the library, which have only 10/100 Mbit/s Ethernet connections to the user device and a Gigabit Ethernet connection to the central router, could be called "layer 3 switches" because they only have Ethernet interfaces and must understand IP. It would be more correct to call them access routers, where the router at the top is a distribution router that connects to the Internet and academic networks' customer access routers.
The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and no need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10 Gbit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100 Gbit/s.[5]
Home area network
A home area network is a residential LAN which is used for communication between digital devices typically deployed in the home, usually a small number of personal computers and accessories, such as printers and mobile computing devices. An important function is the sharing of Internet access, often a broadband service through a CATV or Digital Subscriber Line (DSL) provider.
Campus area network
A campus area network (CAN) is a computer network made up of an interconnection of local area networks (LANs) within a limited geographical area. It can be considered one form of a metropolitan area network, specific to an academic setting. In the case of a university campus-based campus area network, the network is likely to link a variety of campus buildings including; academic departments, the university library and student residence halls. A campus area network is larger than a local area network but smaller than a wide area network (WAN) (in some cases).
The main aim of a campus area network is to facilitate students accessing internet and university resources. This is a network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, office building, or a military base. A CAN may be considered a type of MAN (metropolitan area network), but is generally limited to a smaller area than a typical MAN. This term is most often used to discuss the implementation of networks for a contiguous area. This should not be confused with a Controller Area Network. A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings.
Metropolitan area network
A metropolitan area network (MAN) is a network that connects two or more local area networks or campus area networks together but does not extend beyond the boundaries of the immediate town/city. Routers, switches and hubs are connected to create a metropolitan area network.
Wide area network
A wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances, using a communications channel that combines many types of media such as telephone lines, cables, and air waves. A WAN often uses transmission facilities provided by common carriers, such as telephone companies. WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.
Global area network
A global area network (GAN) is a network used for supporting mobile communications across an arbitrary number of wireless LANs, satellite coverage areas, etc. The key challenge in mobile communications is handing off the user communications from one local coverage area to the next. In IEEE Project 802, this involves a succession of terrestrial WIRELESS local area networks (WLAN).[6]
Virtual private network
A virtual private network (VPN) is a computer network in which some of the links between nodes are carried by open connections or virtual circuits in some larger network (e.g., the Internet) instead of by physical wires. The data link layer protocols of the virtual network are said to be tunneled through the larger network when this is the case. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption. VPNs, for example, can be used to separate the traffic of different user communities over an underlying network with strong security features.
A VPN may have best-effort performance, or may have a defined service level agreement (SLA) between the VPN customer and the VPN service provider. Generally, a VPN has a topology more complex than point-to-point.
Internetwork
An Internetwork is the connection of two or more distinct computer networks via a common routing technology. The result is called an internetwork (often shortened to internet). Two or more networks connect using devices that operate at the Network Layer (Layer 3) of the OSI Basic Reference Model, such as a router. Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork
Internet
The Internet is a global system of interconnected governmental, academic, corporate, public, and private computer networks. It is based on the networking technologies of the Internet Protocol Suite. It is the successor of the Advanced Research Projects Agency Network (ARPANET) developed by DARPA of the U.S. Department of Defense. The Internet is also the communications backbone underlying the World Wide Web (WWW). The 'Internet' is most commonly spelled with a capital 'I' as a proper noun, for historical reasons and to distinguish it from other generic internetworks.
Participants in the Internet use a diverse array of methods of several hundred documented, and often standardized, protocols compatible with the Internet Protocol Suite and an addressing system (IP Addresses) administered by the Internet Assigned Numbers Authority and address registries. Service providers and large enterprises exchange information about the reachability of their address spaces through the Border Gateway Protocol (BGP), forming a redundant worldwide mesh of transmission paths.
Intranets and extranets
Intranets and extranets are parts or extensions of a computer network, usually a local area network. An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity. That administrative entity closes the intranet to all but specific, authorized users. Most commonly, an intranet is the internal network of an organization. A large intranet will typically have at least one web server to provide users with organizational information.
An extranet is a network that is limited in scope to a single organization or entity and also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities (e.g., a company's customers may be given access to some part of its intranet creating in this way an extranet, while at the same time the customers may not be considered 'trusted' from a security standpoint). Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network.
Basic hardware components
All networks are made up of basic hardware building blocks to interconnect network nodes, such as Network Interface Cards (NICs), Bridges, Hubs, Switches, and Routers. In addition, some method of connecting these building blocks is required, usually in the form of galvanic cable (most commonly Category 5 cable). Less common are microwave links (as in IEEE 802.12) or optical cable ("optical fiber"). An Ethernet card may also be required
Network interface cards
A network card, network adapter, or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. It provides physical access to a networking medium and often provides a low-level addressing system through the use of MAC addresses.
Repeaters
A repeater is an electronic device that receives a signal, cleans it from the unnecessary noise, regenerates it and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable which runs longer than 100 meters. Repeaters work on the Physical Layer of the OSI model
Hubs
A network hub contains multiple ports. When a packet arrives at one port, it is copied unmodified to all ports of the hub for transmission. The destination address in the frame is not changed to a broadcast address.[7] It works on the Physical Layer of the OSI model
Bridges
A network bridge connects multiple network segments at the data link layer (layer 2) of the OSI model. Bridges do send broadcasts to all ports except the one on which the broadcast was received. However, bridges do not promiscuously copy traffic to all ports, as hubs do, but learn which MAC addresses are reachable through specific ports. Once the bridge associates a port and an address, it will send traffic for that address to that port only.
Bridges learn the association of ports and addresses by examining the source address of frames that it sees on various ports. Once a frame arrives through a port, its source address is stored and the bridge assumes that MAC address is associated with that port. The first time that a previously unknown destination address is seen, the bridge will forward the frame to all ports other than the one on which the frame arrived.
Bridges come in three basic types:
Local bridges: Directly connect local area networks (LANs)
Remote bridges: Can be used to create a wide area network (WAN) link between LANs. Remote bridges, where the connecting link is slower than the end networks, largely have been replaced with routers.
Wireless bridges: Can be used to join LANs or connect remote stations to LANs
Switches
A network switch is a device that forwards and filters OSI layer 2 datagrams (chunk of data communication) between ports (connected cables) based on the MAC addresses in the packets.[8] This is distinct from a hub in that it only forwards the frames to the ports involved in the communication rather than all ports connected. A switch breaks the collision domain but represents itself a broadcast domain. Switches make forwarding decisions of frames on the basis of MAC addresses. A switch normally has numerous ports, facilitating a star topology for devices, and cascading additional switches.[9] Some switches are capable of routing based on Layer 3 addressing or additional logical levels; these are called multi-layer switches. The term switch is used loosely in marketing to encompass devices including routers and bridges, as well as devices that may distribute traffic on load or by application content (e.g., a Web URL identifier).
Routers
A router is a networking device that forwards packets between networks using information in protocol headers and forwarding tables to determine the best next router for each packet.
blogs
A blog (a contraction of the term "web log")[1] is a type of website, usually maintained by an individual with regular entries of commentary, descriptions of events, or other material such as graphics or video. Entries are commonly displayed in reverse-chronological order. "Blog" can also be used as a verb, meaning to maintain or add content to a blog.
Many blogs provide commentary or news on a particular subject; others function as more personal online diaries. A typical blog combines text, images, and links to other blogs, Web pages, and other media related to its topic. The ability of readers to leave comments in an interactive format is an important part of many blogs. Most blogs are primarily textual, although some focus on art (Art blog), photographs (photoblog), videos (Video blogging), music (MP3 blog), and audio (podcasting). Microblogging is another type of blogging, featuring very short posts.
As of December 2007, blog search engine Technorati was tracking more than 112,000,000 blogs.[2]
Types
There are many different types of blogs, differing not only in the type of content, but also in the way that content is delivered or written.
Personal blogs
The personal blog, an ongoing diary or commentary by an individual, is the traditional, most common blog. Personal bloggers usually take pride in their blog posts, even if their blog is never read. Blogs often become more than a way to just communicate; they become a way to reflect on life, or works of art. Blogging can have a sentimental quality. Few personal blogs rise to fame and the mainstream, but some personal blogs quickly garner an extensive following. One type of personal blog, referred to as a microblog, is extremely detailed and seeks to capture a moment in time. Some sites, such as Twitter, allow bloggers to share thoughts and feelings instantaneously with friends and family, and are much faster than emailing or writing.
Corporate and organizational blogs
A blog can be private, as in most cases, or it can be for business purposes. Blogs used internally to enhance the communication and culture in a corporation or externally for marketing, branding or public relations purposes are called corporate blogs. Similar blogs for clubs and societies are called club blogs, group blogs, or by similar names; typical use is to inform members and other interested parties of club and member activities.
By genre
Some blogs focus on a particular subject, such as political blogs, travel blogs (also known as travelogs), house blogs,[3][4] fashion blogs, project blogs, education blogs, niche blogs, classical music blogs, quizzing blogs and legal blogs (often referred to as a blawgs) or dreamlogs. Two common types of genre blogs are art blogs and music blogs. A blog featuring discussions especially about home and family is not uncommonly called a mom blog.[5][6][7][8][9] While not a legitimate type of blog, one used for the sole purpose of spamming is known as a Splog.
By media type
A blog comprising videos is called a vlog, one comprising links is called a linklog, a site containing a portfolio of sketches is called a sketchblog or one comprising photos is called a photoblog.[10] Blogs with shorter posts and mixed media types are called tumblelogs. Blogs that are written on typewriters and then scanned are called typecast or typecast blogs; see typecasting (blogging).
A rare type of blog hosted on the Gopher Protocol is known as a Phlog.
By device
Blogs can also be defined by which type of device is used to compose it. A blog written by a mobile device like a mobile phone or PDA could be called a moblog.[11] One early blog was Wearable Wireless Webcam, an online shared diary of a person's personal life combining text, video, and pictures transmitted live from a wearable computer and EyeTap device to a web site. This practice of semi-automated blogging with live video together with text was referred to as sousveillance. Such journals have been used as evidence in legal matters.[citation needed]
Internet radio (also known as web radio, net radio, streaming radio and e-radio) is an audio service transmitted via the Internet. Music streaming on the Internet is usually referred to as webcasting since it is not transmitted broadly through wireless means.
Internet radio involves streaming media, presenting listeners with a continuous stream of audio that cannot be paused or replayed, much like traditional broadcast media; in this respect, it is distinct from on-demand file serving. Internet radio is also distinct from podcasting, which involves downloading rather than streaming. Many Internet radio services are associated with a corresponding traditional (terrestrial) radio station or radio network. Internet-only radio stations are independent of such associations.
Internet radio services are usually accessible from anywhere in the world—for example, one could listen to an Australian station from Europe or America. Some major networks like CBS Radio in the US and Chrysalis in the UK restrict listening to in country because of music licensing and advertising concerns.[citation needed] Internet radio remains popular among expatriates and listeners with interests that are often not adequately served by local radio stations (such as eurodance, progressive rock, ambient music, folk music, classical music, and stand-up comedy). Internet radio services offer news, sports, talk, and various genres of music—every format that is available on traditional radio stationsvvvvv
A satellite radio or subscription radio (SR) is a digital radio signal that is broadcast by a communications satellite, which covers a much wider geographical range than terrestrial radio signals.
Satellite radio offers a meaningful alternative to ground-based radio services in some countries, notably the United States. Mobile services, such as Sirius, XM, and Worldspace, allow listeners to roam across an entire continent, listening to the same audio programming anywhere they go. Other services, such as Music Choice or Muzak's satellite-delivered content, require a fixed-location receiver and a dish antenna. In all cases, the antenna must have a clear view to the satellites. In areas where tall buildings, bridges, or even parking garages obscure the signal, repeaters can be placed to make the signal available to listeners.
Radio services are usually provided by commercial ventures and are subscription-based. The various services are proprietary signals, requiring specialized hardware for decoding and playback. Providers usually carry a variety of news, weather, sports, and music channels, with the music channels generally being commercial-free.
In areas with a relatively high population density, it is easier and less expensive to reach the bulk of the population with terrestrial broadcasts. Thus in the UK and some other countries, the contemporary evolution of radio services is focused on Digital Audio Broadcasting (DAB) services or HD Radio, rather than satellite radio.
A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring. Data travels from node to node, with each node along the way handling every packet.
Because a ring topology provides only one pathway between any two nodes, ring networks may be disrupted by the failure of a single link. A node failure or cable break might isolate every node attached to the ring. FDDI networks overcome this vulnerability by sending data on a clockwise and a counterclockwise ring: in the event of a break data is wrapped back onto the complementary ring before it reaches the end of the cable, maintaining a path to every node along the resulting "C-Ring". 802.5 networks -- also known as IBM Token Ring networks -- avoid the weakness of a ring topology altogether: they actually use a star topology at the physical layer and a Multistation Access Unit (MAU) to imitate a ring at the datalink layer.
Many ring networks add a "counter-rotating ring" to form a redundant topology. Such "dual ring" networks include Spatial Reuse Protocol, Fiber Distributed Data Interface (FDDI), and Resilient Packet Ring.
A bus network topology
A bus network topology is a network architecture in which a set of clients are connected via a shared communications line, called a bus. There are several common instances of the bus architecture, including one in the motherboard of most computers, and those in some versions ofEthernet networks.
Bus networks are the simplest way to connect multiple clients, but may have problems when two clients want to transmit at the same time on the same bus. Thus systems which use bus network architectures normally have some scheme of collision handling or collision avoidance for communication on the bus, quite often using Carrier Sense Multiple Access or the presence of a bus master which controls access to the shared bus resource.
A true bus network is passive – the computers on the bus simply listen for a signal; they are not responsible for moving the signal along. However, many active architectures can also be described as a "bus", as they provide the same logical functions as a passive bus; for example, switched Ethernet can still be regarded as a logical network, if not a physical one. Indeed, the hardware may be abstracted away completely in the case of a software bus.
With the dominance of switched Ethernet over passive Ethernet, passive bus networks are uncommon in wired networks. However, almost all current wireless networks can be viewed as examples of passive bus networks, with radio propagation serving as the shared passive medium.
The bus topology makes the addition of new devices straightforward. The term used to describe clients is station or workstation in this type of network. Bus network topology uses a broadcast channel which means that all attached stations can hear every transmission and all stations have equal priority in using the network to transmit[1] data.
The Ethernet bus topology works like a big telephone party line — before any device can send a packet, devices on the bus must first determine that no other device is sending a packet on the cable. When a device sends its packet out over the bus, every other network card on the bus sees and reads the packet. Ethernet’s scheme of having devices communicate like they were in chat room is called Carrier Sense Multiple Access/ Collision Detection (CSMA/CD). Sometimes two cards talk (send packets) at the same time. This creates a collision, and the cards themselves arbitrate to decide which one will resend its packet first. All PCs on a bus network share a common wire, which also means they share the data transfer capacity of that wire – or, in tech terms, they share its bandwidth.
This creates an interesting effect. Ten PCs chatting on a bus each get to use a much higher proportion of its total bandwidth than, for instance, 100 PCs on the same bus (in this case, one – tenth compared to one – hundredth). The more PCs on a bus, the more likely you’ll have a communication traffic jam. [2]
Star networks
Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central switch,hub or computer, which acts as a conduit to transmit messages.[1] Thus, the hub and leaf nodes, and the transmission lines between them, form a graph with the topology of a star. If the central node is passive, the originating node must be able to tolerate the reception of an echo of its own transmission, delayed by the two-way transmission time (i.e. to and from the central node) plus any delay generated in the central node. Anactive star network has an active central node that usually has the means to prevent echo-related problems.
The star topology reduces the chance of network failure by connecting all of the systems to a central node. When applied to a bus-based network, this central hub rebroadcasts all transmissions received from any peripheral node to all peripheral nodes on the network, sometimes including the originating node. All peripheral nodes may thus communicate with all others by transmitting to, and receiving from, the central node only. The failure of a transmission line linking any peripheral node to the central node will result in the isolation of that peripheral node from all others, but the rest of the systems will be unaffected. [2]
It is also designed with each node (file wrver, workstations, and peripherals) connected directly to a central network hub, switch, or concentrator.
Data on a star network passes through the hub, switch, or concentrator before continuing to its destination. The hub, switch, or concentrator manages and controls all functions of the network. It is also acts as a repeater for the data flow. This configuration is common with twisted pair cable. However, it can also be used with coaxial cable or optical fibre cable.
A bulletin board
A bulletin board (pinboard, pin board or notice board in British English) is a place where people can leave public messages, for example, to advertise things to buy or sell, announce events, or provide information. Bulletin boards are often made of a material such as cork to facilitate addition and removal of messages or it can be placed on the computer so people can leave and erase messages for other people to read and see.
Bulletin boards are particularly prevalent at universities. Many sport dozens, if not hundreds or thousands of public bulletin boards, used for everything from advertisements by extracurricular groups and local shops to official notices. Dormitory corridors, well-trafficked hallways, lobbies, and freestanding kiosks often have cork boards attached to facilitate the posting of notices. At some universities, lampposts, bollards, trees, and walls often become impromptu posting sites in areas where official boards are sparse in number.
Internet forums are becoming a global replacement for traditional bulletins. Online bulletin boards are sometimes referred to as message boards. The terms bulletin board, message boards and even internet forums are interchangeable, although often one bulletin board or message board can contain a number of internet forums or discussion groups. An online board can serve the same purpose as a physical bulletin board.
psychology
Pre-natal development
See also: Pre-natal development and Pre- and perinatal psychology
Pre-natal development is of interest to psychologists investigating the context of early psychological development. For example, some primitive reflexes arise before birth and are still present in newborns. One hypothesis is that these reflexes are vestigial and have limited use in early human life. Piaget's Theory of cognitive development suggested that some early reflexes are building blocks for infant sensorimotor development. For example the tonic neck reflex may help development by bringing objects into the infant's field of view[9]. Other reflexes, such as the walking reflex disappear to be replaced by more sophisticated voluntary control later in infancy. This may be because the infant gains too much weight after birth to be strong enough to use the reflex, or because the reflex and subsequent development are functionally different[10]. It has also been suggested that some reflexes (for example the moro and walking reflexes) are predominantly adaptations to life in the womb with little connection to early infant development[9]. Primitive reflexes reappear in adults under certain conditions, such as neurological conditions like dementia or traumatic lesions.
Ultrasound has shown that infants are capable of a range of movements in the womb, many of which appear to be more than simple reflexes[10]. By the time they are born, infants can recognise and have a preference for their mother's voice suggesting some pre-natal development of auditory perception[10]. Pre-natal development and birth complications may also be connected to neurodevelopmental disorders, for example in schizophrenia. With the advent of cognitive neuroscience, embryology and the neuroscience of pre-natal development is of increasing interest to developmental psychology research.
Infancy
Main articles: Infant and child psychology and
Infant cognitive development
From birth until the onset of speech, the child is referred to as an infant. Developmental psychologists vary widely in their assessment of infant psychology, and the influence the outside world has upon it, but certain aspects are relatively clear.
The majority of a newborn infant's time is spent in sleep. At first this sleep is evenly spread throughout the day and night, but after a couple of months, infants generally become diurnal.
Infants can be seen to have 6 states, grouped into pairs:
§ quiet sleep and active sleep (dreaming, when
REM occurs)
§ quiet waking, and active waking
§ fussing and crying
Infants respond to stimuli differently in these different states[10].
Habituation (see above) has been used to discover the resolution of perceptual systems, suggesting that infants basic perceptual abilities develop before acquisition of object permanence.
§ Vision is significantly worse in infants than in older children. Infant sight, blurry in early stages, improves over time. Colour perception similar to that seen in adults has been demonstrated in infants as young as four months, using habituation methods
[9].
§ Hearing is well-developed prior to birth, however, and a preference for the mother's heartbeat is well established. Infants are fairly good at detecting the direction from which a sound comes, and by 18 months their hearing ability is approximately equal to that of adults.
§ Smell and taste are present, with infants showing different expressions of disgust or pleasure when presented with pleasant odors (honey, milk, etc) or unpleasant odors (rotten egg) and tastes (e.g. sour taste). There is good evidence for infants preferring the smell of their mother to that of others
[9].
§ Language : infants of around six months can differentiate between phonemes in their own language, but not between similar phonemes in another language. At this stage infants also start to babble, producing phonemes.
§ Touch is one of the better developed senses at birth, being one of the first to develop inside the womb. This is evidenced by the
primitive reflexes described above, and the relatively advanced development of the somatosensory cortex[11].
§ Pain : Infants feel pain similarly, if not more strongly than older children but pain-relief in infants has not received so much attention as an area of research[12].
An early theory of infant development was the
Sensorimotor stage of Piaget's Theory of cognitive development. Piaget suggested that an infant's perception and understanding of the world depended on their motor development, which was required for the infant to link visual, tactile and motor representations of objects. According to this view, it is through touching and handling objects that infants develop object permanence, the understanding that objects are solid, permanent, and continue to exist when out of sight[10].
Piaget's Sensorimotor Stage comprised six sub-stages (see sensorimotor stages for more detail). In the early stages, development arises out of movements caused by primitive reflexes[13]. Discovery of new behaviours results from classical and operant conditioning, and the formation of
habits[13]. From eight months the infant is able to uncover a hidden object but will persevere when the object is moved. Piaget's evidence for an incomplete understanding of object permanence before 18 months was the infant's failure to look for an object where it was last seen. Instead infants continue to look for an object where it was first seen, committing the "A-not-B error".
Later researchers have developed a number of other tests which suggest that younger infants understand more about objects than first thought. These experiments usually involve a toy, and a crude barrier which is placed in front of the toy, and then removed, repeatedly. Before the age of eight to nine months, infants inability to understand object permanence extends to people, which explains why infants at this age do not cry when their mothers are gone ("Out of sight, out of mind.").
There are critical periods in infancy and childhood during which development of certain perceptual, sensorimotor, social and language systems depends crucially on environmental stimulation
[14]. Feral children such as Genie, deprived of adequate stimulation, fail to acquire important skills which they are then unable to learn in later childhood. The concept of critical periods is also well established in neurophysiology, from the work of Hubel and Wiesel among others. Some feel that
classical music, particularly Mozartis good for an infant's mind. While some tentative research has shown it to be helpful to older children, no conclusive evidence is available involving infants. [15]
Babyhood
Intelligence is demonstrated through the use of symbols, language use matures, and memory and imagination are developed. Thinking is done in a nonlogical, nonreversible manner.
Egocentric thinking predominates.
Socially, toddlers are little people attempting to become independent at this stage, which they are commonly called the " terrible twos". They walk, talk, use the toilet, and get food for themselves. Self-control begins to develop. If taking the initiative to explore, experiment, risk mistakes in trying new things, and test their limits is encouraged by the caretaker(s) the child will become autonomous, self-reliant, and confident. If the caretaker is overprotective or disapproving of independent actions, the toddler may begin to doubt their abilities and feel ashamed for the desire for independence. The child's autonomic development will be inhibited, and be less prepared to successfully deal with the world in the future.
Early childhood
Also called as "Pre-school age", "Pre-gang age", "Exploratory age" and "Toy age".
When children attend preschool, they broaden their social horizons and become more engaged with those around them. Impulses are channeled into fantasies, which leaves the task of the caretaker to balance eagerness for pursuing adventure, creativity and self expression with the development of responsibility. If caretakers are properly encouraging and consistently disciplinary, children are more likely to develop positive self-esteem while becoming more responsible, and will follow through on assigned activities.[citation needed] If not allowed to decide which activities to perform, children may begin to feel guilt upon contemplating taking initiative.[
citation needed] This negative association with independence will lead them to let others make decisions in place of them.
Late Childhood
In middle childhood, intelligence is demonstrated through logical and systematic manipulation of symbols related to concrete objects. Operational thinking develops, which means actions are reversible, and egocentric thought diminishes.
Children go through the transition from the world at home to that of school and peers. Children learn to make things, use tools, and acquire the skills to be a worker and a potential provider. Children can now receive feedback from outsiders about their accomplishments. If children can discover pleasure in intellectual stimulation, being productive, seeking success, they will develop a sense of competence. If they are not successful or cannot discover pleasure in the process, they may develop a sense of inferiority and feelings of inadequacy that may haunt them throughout life. This is when children think of them selves as industrious or as inferior.
Adolescence
Main article: Adolescent psychology
Adolescence is the period of life between the onset of puberty and the full commitment to an adult social role, such as worker, parent, and/or citizen. It is the period known for the formation of personal and social identity (see Erik Erikson) and the discovery of moral purpose (see William Damon). Intelligence is demonstrated through the logical use of symbols related to abstract concepts and formal reasoning. A return to
egocentric thought often occurs early in the period. Only 35% develop the capacity to reason formally during adolescence or adulthood. (Huitt, W. and Hummel, J. January 1998)[16]
It is divided into two parts namely:
1. Early Adolescence: 13 to 17 years and
2. Late Adolescence: 17 to 18 years
The adolescent unconsciously explores questions such as "Who am I? Who do I want to be?" Like toddlers, adolescents must explore, test limits, become autonomous, and commit to anidentity, or
sense of self. Different roles, behaviors and ideologies must be tried out to select an identity. Role confusion and inability to choose vocation can result from a failure to achieve a sense of identity.
Early adulthood
The person must learn how to form intimate relationships, both in friendship and love. The development of this skill relies on the resolution of other stages. It may be hard to establish intimacy if one has not developed trust or a sense of identity. If this skill is not learned the alternative is alienation, isolation, a fear of commitment, and the inability to depend on others.
A related framework for studying this part of the life span is that of
Emerging adulthood, introduced in 2000 by Jeffrey Arnett. Scholars of emerging adulthood are interested not only in relationship development (focusing on the role of dating in helping individuals settle on a long-term spouse/partner), but also the development of sociopolitical views and occupational choice.
Middle age
Middle adulthood generally refers to the period between ages 40 to 60. During this period, the middle-aged experience a conflict between generativity and stagnation. They may either feel a sense of contributing to the next generation and their community or a sense of purposelessness.
Physically, the middle-aged experience a decline in muscular strength, reaction time, sensory keenness, and cardiac output. Also, women experience menopause and a sharp drop in the hormone
estrogen. Men do have an equivalent to menopause, it is called "Andropause," which is a hormone fluctuation with physical and psychological effects similar to menopause. Lowered testosterone levels result in mood swings and a decline in sperm count and speed of ejaculation and erection. Most men and women remain capable of sexual satisfaction after middle age.
Old age
This stage generally refers to those over 60-80 years. During old age, people experience a conflict between integrity vs. despair. When reflecting on their life, they either feel a sense of accomplishment or failure.
Physically, older people experience a decline in muscular strength, reaction time, stamina, hearing, distance perception, and the sense of smell. They also are more susceptible to severe diseases such as cancer and pneumonia due to a weakened immune system. Mental disintegration may also occur, leading to Dementia or Alzheimer's Disease. However, partially due to a lifetime's accumulation of antibodies, the elderly are less likely to suffer from common diseases such as the cold.
Whether or not intellectual powers increase or decrease with age remains controversial. Longitudinal studies have suggested that intellect declines, while cross-sectional studies suggest that intellect is stable. It is generally believed that
crystallized intelligence increases up to old age, while fluid intelligence decreases with age.
Crowd psychology is a branch of social psychology. Ordinary people can typically gain direct power by acting collectively. Historically, because large groups of people have been able to bring about dramatic and sudden social change in a manner that bypasses established due process, they have also provoked controversy. Social scientists have developed several different theories for explaining crowd psychology, and the ways in which the psychology of the crowd differs significantly from the psychology of those individuals within it. Carl Jung coined the notion of the Collective unconscious. Other major thinkers of crowd psychology include
Gustave Le Bon, Wilfred Trotter, Gabriel Tarde, Sigmund Freud and Elias Canetti.
Theory of information
Overview
The main concepts of information theory can be grasped by considering the most widespread means of human communication: language. Two important aspects of a concise language are as follows: First, the most common words (e.g., "a", "the", "I") should be shorter than less common words (e.g., "benefit", "generation", "mediocre"), so that sentences will not be too long. Such a tradeoff in word length is analogous to data compression and is the essential aspect of source coding. Second, if part of a sentence is unheard or misheard due to noise — e.g., a passing car — the listener should still be able to glean the meaning of the underlying message. Such robustness is as essential for an electronic communication system as it is for a language; properly building such robustness into communications is done by channel coding. Source coding and channel coding are the fundamental concerns of information theory.
Note that these concerns have nothing to do with the importance of messages. For example, a platitude such as "Thank you; come again" takes about as long to say or write as the urgent plea, "Call an ambulance!" while the latter may be more important and more meaningful in many contexts. Information theory, however, does not consider message importance or meaning, as these are matters of the quality of data rather than the quantity and readability of data, the latter of which is determined solely by probabilities.
Information theory is generally considered to have been founded in 1948 by Claude Shannon in his seminal work, "A Mathematical Theory of Communication." The central paradigm of classical information theory is the engineering problem of the transmission of information over a noisy channel. The most fundamental results of this theory are Shannon's source coding theorem, which establishes that, on average, the number of bits needed to represent the result of an uncertain event is given by its entropy; and Shannon's noisy-channel coding theorem, which states that reliable communication is possible over noisy channels provided that the rate of communication is below a certain threshold called the channel capacity. The channel capacity can be approached in practice by using appropriate encoding and decoding systems.
Information theory is closely associated with a collection of pure and applied disciplines that have been investigated and reduced to engineering practice under a variety of rubrics throughout the world over the past half century or more: adaptive systems, anticipatory systems, artificial intelligence, complex systems, complexity science, cybernetics, informatics, machine learning, along with systems sciences of many descriptions. Information theory is a broad and deep mathematical theory, with equally broad and deep applications, amongst which is the vital field of coding theory.
Coding theory is concerned with finding explicit methods, called codes, of increasing the efficiency and reducing the net error rate of data communication over a noisy channel to near the limit that Shannon proved is the maximum possible for that channel. These codes can be roughly subdivided into data compression (source coding) and error-correction (channel coding) techniques. In the latter case, it took many years to find the methods Shannon's work proved were possible. A third class of information theory codes are cryptographic algorithms (bothcodes and ciphers). Concepts, methods and results from coding theory and information theory are widely used in cryptography and cryptanalysis. See the article ban (information) for a historical application.
Information theory is also used in information retrieval, intelligence gathering, gambling, statistics, and even in musical composition.
