The stronger the connection between the ideas, the more quickly the person is able to recall relevant information. A person can probably verify very quickly the statement "A bird is an animal," because birds are very common, typical examples of the category "animal. The model of spreading activation would account for this difficulty by saying that the node for "chinchilla" would not necessarily be activated by the category "animal.
Of course, the associations between semantic concepts vary greatly from person to person. Someone who has a pet chinchilla, for example, will have far greater connections between "animal" and "chinchilla" than the general population. In this way, the semantic categories described by spreading activation are a product both the actual content and of the individual experience. Also called arousal theory. When part of the memory network is activated , activation spreads along the associative pathways to related areas in memory.
Define spreading activation. Spreading activation is a method for searching associative networks, biological and artificial neural networks, or semantic networks. Activation , also called arousal, in psychology , the stimulation of the cerebral cortex into a state of general wakefulness, or attention. Which approach to categorization can more easily take into account atypical cases such as flightless birds?
An advantage of the exemplar approach over the prototype approach is that the exemplar approach provides a better explanation of the effect. Tversky and his colleagues have published a few papers lending support to the contrast model. For example, Tversky and Gati have used the contrast model to explain asymmetric similarity judgments. They have shown that subjects' judged similarity of North Korea to China exceeds their judged similarity of China to North Korea.
In a consumption context, Johnson has found that consumers rated the similarity of shasta cola to coca cola to be higher than the similarity of coca cola to shasta cola. Thus, coke is not as similar to shasta as shasta is to coke. Tversky and Gati explain this asymmetry via a focusing hypothesis and a relative salience effect in their contrast model. The focusing hypothesis states that if S a,b is interpreted as the degree to which 'a' subject is similar to 'b' referent then in such judgments attributes of 'a' are weighted more heavily than attributes of 'b' i.
The salience effect follows from the contrast model. While the explanation provided by Tversky and Gati is reasonable, however, it is not grounded in the memory network models. For example, how are 'subject' and 'referent' cognitivly represented and how features or attributes are given more weight than less.
In the following section a memory network model of asymmetric similarity judgment is presented. Assume that 'a' e. This node is linked to many attributes like carbonated, refreshing, dark color, sweet taste, distinctive bottle, etc. If A is the set of these attributes of coke then node 'Coke' has A different links emanating from it. Similarly, node 'b' e. Thus, the network structure might be represented as in Figure 1. The focusing hypothesis of Tversky and Gati is proposed to be captured by a priming effect.
According to Tversky and Gati when coke is the subject and shasta the referent, then the attributes of coke are weighted more heavily than the attributes of shasta.
However, they also suggest that human subjects have a propensity to use directional statements such as "x is like y" where the subject 'x' always comes before the referent 'y' in similarity statements.
A case can be made that the subject 'x' is acting as a prime for the referent 'y'. Thus, in a similarity estimation of coke to shasta, it is proposed that coke acts as a prime for shasta. The salience of a stimulus depends on factors which include intensity, familiarity, frequency, informational content among others Tversky and Gati All of these factors may safely be assumed to give rise to two phenomenon. Firstly, they will increase the steady state level of activation of a node Anderson Secondly, they will increase the number of links emanating from a node as well as their strengths Collins and Loftus Thus in the previous diagram, coke is more salient than shasta coke has more links than shasta.
Because of the 'fan effect', however, 'Coke' will be able to spread a lesser amount of activation to 'Shasta' via the common links as compared to that sent by 'Shasta' to 'Coke', assuming that the two have an equal amount of steady state activation level. The process of asymmetric similarity judgments between coke and shasta can now be grounded into a proposed semantic network model. When a subject is judging the degree to which shasta is similar to coke, node 'Shasta' becomes the focused unit.
Activation spreads from 'Shasta' via the mediating common attributes to 'Coke' Balota and Lorch The strength of activation reaching 'Coke' depends on the sum of weights of the common links between 'Shasta' and 'Coke' relative to the weights of all links emanating from 'Shasta'. The speed with which the intersection of activations from 'Shasta' and 'Coke' takes place, and the information about the level of activation which is available to the subject; Anderson guides the subject to decide on the similarity of shasta to coke.
A similar process occurs when the subject is determining the degree to which coke is similar to shasta. If we assume that the steady state activation level of shasta and coke are the same and also that coke is more salient than shasta, then because of the fan effect less activation will reach shasta from coke, as coke has many more links which also have greater strength, while more activation will reach coke from shasta. Because of this difference in activation transfer, the speed with which a critical level of activation intersection is reached will be more in the case when shasta is the prime than when coke is the prime Anderson The information of this level of activation at the intersection is proposed to result in a degree of similarity judgment.
According to the 'semantic relatedness effect' those concepts that are highly interrelated can be judged more rapidly in a lexical task than those with lower degrees of relatedness Ashcraft Thus, speed of spreading activation and relatedness or similarity in this case are related.
The more the activation spreads, the sooner the intersection, and consequently the more similar the prime concept is to the target concept. Thus, shasta will be reported as more similar to coke than vice versa. This asymmetric similarity judgment is exactly the same as that obtained by Johnson However, the proposed model presented in this paper provides asymmetric similarity judgment a grounding in memory network models.
Based on the above logic we would hypothesize the following:. A more salient brand within a product category, when used as a prime, will slow the lexical decision or pronunciation task for a less salient target brand within the same product category. Thus, the more salient brand will be judged as 'less' similar to less salient brand.
On the other hand, a less salient brand within a product category, when used as a prime, will facilitate the lexical decision or pronunciation task for a more salient target brand within the same product category.
Thus, the less salient brand will be judged as 'more' similar to more salient brand. A spreading activation model of consumer's asymmetric similarity judgment is proposed. The model, if validated by empirical data, could lead to many interesting implications in the area of consumer's memory of brands and choice process. Firstly, it directly impacts on the contents of a consumer's evoked set. It seems that because of differential activation capabilities of less salient and more salient brands the composition of evoked set will depend on the 'cue' brand.
If the cue brand is less salient then the probability of recall of more salient brand will be high and so will be its probability of being a member of the evoked set. On the other hand, if the cue brand is more salient then the probability of recall, and hence membership in evoked set, of a less salient brand will be low. Secondly, if according to this model priming has an important role to play in similarity judgment then an area of automatic and controlled similarity judgment might evolve.
Posner and Snyder had shown that automatic priming precedes controlled processes. Thus, one may argue that in a low involvement choice process, where controlled processes are not dominant, automatic activation of brands may determine the similarity judgments among brands.
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