accessibility, principle of

n. A unit of knowledge cannot be activated, or brought to a person’s mind, unless it is present in that person’s memory. Knowledge availability refers to whether or not a knowledge unit is actually stored in memory. Knowledge accessibility refers to the activation potential of an available knowledge unit. The term potential in the definition of accessibility captures the fact that accessible knowledge is capable of being activated (and then used), but it exists in a latent rather than in an active state. The word potent, the root of potential, captures the property of accessibility that it contributes to the likelihood that the knowledge will be used in judgments, inferences, and other responses. The term potential also includes notions of energy or effectiveness from chemical or electrical properties or from the position of a piece of matter in an arrangement, and these notions cover the major models that have been proposed for understanding the nature and functions of accessibility.
Two basic types of models have been used to understand the nature of knowledge accessibility and its effects - mechanistic models and excitation transmission models. Mechanistic models understand accessibility in terms of the arrangement and the working of stored component parts. In contrast, excitation transmission models understand accessibility in terms of the heightening and the dissipation of excitation (or energy levels) from stimulation and decay. These models differ in their assumptions about the interrelations among accessibility, activation, and stimulus input.
In mechanistic models, a knowledge unit that has been recently or frequently activated has a position within the structural arrangement of categories that makes it likely to be retrieved first. Once activated, the knowledge unit is then compared to the stimulus input and its use in judgment or inference depends on there being a reasonably good fit between the knowledge unit and the input. In excitation transmission models, the accessibility of the knowledge unit and the input features that match the category both contribute to the excitation level of the knowledge unit, which determines whether it becomes activated in the first place. If a knowledge unit has very low accessibility, then the fit between it and the input must be very good for it to become activated. On the other hand, if a knowledge unit has very high accessibility, then the fit between it and the input need not be good for it to become activated because the accessibility will compensate for the poor fit.
The accessibility of an available knowledge unit can be increased temporarily by priming or recently activating the unit prior to the situation in which the knowledge might be used. Many studies have found that prior exposure to a knowledge-related word in one situation, even subliminally, increases the likelihood that the knowledge will be used several minutes later to make a judgment in a different situation. Such priming effects on judgment can occur automatically outside people’s conscious awareness.
A stored knowledge unit can also be primed frequently over an extended period, causing it to have relatively high accessibility for a long time afterward - a property called high chronic accessibility. There are personality, developmental, and cultural differences in chronic accessibility. The most common measure of individuals’ chronically accessible social knowledge involves asking a person to list the traits or characteristics of a type of person whom he or she likes, dislikes, seeks out, avoids, and frequently encounters. Chronic accessibility is defined in terms of output primacy and/or frequency. A person has high chronic accessibility for a given knowledge unit if he or she lists that unit first in response to one or more questions and/ or lists it frequently in response to the questions. A person has low chronic accessibility for a given knowledge unit (i.e., nonchronic) if he or she does not list the category in response to any question. Studies have found that chronically accessible social knowledge units can be relatively stable for months or even years, and they influence memory, impressions, and behavior. Another important kind of knowledge is attitudes, which also vary in their chronic accessibility. The most common measure of attitude accessibility involves asking people about their attitudes, such as asking them to evaluate whether each attitude object is “good” or “bad” and measuring the speed with which each person responds to the inquiry. The faster the response, the higher the accessibility. Higher attitude accessibility, in turn, predicts greater consistency between a person’s attitude toward some object and his or her behavior toward that object.     - ETH