Cognitive psychological approaches to similarity

Similarity refers to the psychological nearness or proximity of two mental representations. Research in cognitive psychology

Cognitive psychology

Cognitive psychology is a subdiscipline of psychology exploring internal mental processes.It is the study of how people perceive, remember, think, speak, and solve problems.Cognitive psychology differs from previous psychological approaches in two key ways....

 has taken a number of approaches to the concept of similarity. Each of them is related to a particular set of assumptions about knowledge representation

Knowledge representation

Knowledge representation is an area of artificial intelligence research aimed at representing knowledge in symbols to facilitate inferencing from those knowledge elements, creating new elements of knowledge...

.

Mental distance approaches (Shepard, 1962) assume that mental representations can be conceptualized as some kind of mental space. Concepts are represented as points within the space. Similarity between concepts is a function of the distance between the concepts in space. Concepts represented by points that are near to each other are more psychologically similar than are points that are conceptually distant. A strength of this approach is there are many mathematical techniques for deriving spaces from data such as multidimensional scaling

Multidimensional scaling

Multidimensional scaling is a set of related statistical techniques often used in information visualization for exploring similarities or dissimilarities in data. MDS is a special case of ordination. An MDS algorithm starts with a matrix of item–item similarities, then assigns a location to each...

 (Shepard, 1962) and latent semantic analysis

Latent semantic analysis

Latent semantic analysis is a technique in natural language processing, in particular in vectorial semantics, of analyzing relationships between a set of documents and the terms they contain by producing a set of concepts related to the documents and terms. LSA assumes that words that are close...

 (Laudauer & Dumais, 1997).

Featural approaches

Featural approaches (Tversky, 1977) were developed to address limitations of the mental distance approaches. For example, spaces are symmetric. The distance between two points is the same regardless of which point you start from. However, psychological similarity is not symmetric. For example, we often prefer to state similarity in one direction. For example, it feels more natural to say that 101 is like 100 than to say that 100 is like 101. Furthermore, many metaphor

Metaphor

A metaphor is a literary figure of speech that uses an image, story or tangible thing to represent a less tangible thing or some intangible quality or idea; e.g., "Her eyes were glistening jewels." Metaphor may also be used for any rhetorical figures of speech that achieve their effects via...

s are also directional. Saying "That surgeon is a butcher" means something quite different from saying "That butcher is a surgeon."

Featural approaches assumed that people represent concepts by lists of features that describe properties of the items. A similarity comparison involves comparing the feature lists that represent the concepts. Features that are shared in the feature lists are commonalities of the pair and features that are contained in one feature set but not the other are differences of the pair. It is possible to account for people's intuitions or ratings of the similarities between concepts by assuming that judgments of similarity increase with the number of commonalities (weighted by the salience of those commonalities) and decreases with the number of differences (weighted by the salience of the differences).

Structural approaches

Structural approaches to similarity (Gentner & Markman, 1997) were developed to address limitations of the featural account. In particular, featural approaches assume that the commonalities and differences are independent of each other. However, commonalities and differences are not psychologically independent. In fact, determining the differences between a pair requires finding the commonalities. Consider the comparison between a car and a motorcycle. Both have wheels. That is a commonality. However, cars have four wheels, while motorcycles have two wheels. That is a difference. Because this difference required first finding a commonality between the pair, it is called an alignable difference. Alignable differences contrast with nonalignable differences which are aspects of one concept that have no correspondence in the other. For example, cars have seatbelts and motorcycles do not. Research suggests that alignable differences have a larger impact on people's judgments of similarity than do nonalignable differences. Thus, the relationship between the commonalities of a pair and the differences is important for understanding people's assessments of similarity. Structural approaches to similarity emerged from research on analogy

Analogy

Analogy is a cognitive process of transferring information or meaning from a particular subject to another particular subject , and a linguistic expression corresponding to such a process...

.

Transformational approaches

Transformational accounts of similarity (Hahn & Chater, 2003) were developed to evaluate similarity independently of the type of mental representation. On this view, any mental representation can be transformed into another mental representation through some series of steps. For any representation system and set of transformations, it is possible to define the shortest set of steps (i.e., the shortest program) that will transform one representation into another. The shorter this minimal program, the more similarity the pair of concepts. Larkey and Markman (2005) found some evidence against this view, showing that the number of steps to transform the colors and shapes of geometric objects does not predict people's similarity judgments for those objects.

Social psychological approaches

In social psychology

Social psychology

Social psychology is the scientific study of how people's thoughts, feelings, and behaviors are influenced by the actual, imagined, or implied presence of others. By this definition, scientific refers to the empirical method of investigation. The terms thoughts, feelings, and behaviors include all...

, similarity refers to how closely attitudes, values, interests and personality match between people. Research has consistently shown that similarity leads to interpersonal attraction

Interpersonal attraction

Interpersonal attraction is the attraction between people which leads to friendships and romantic relationships. Interpersonal attraction, the process, is distinct from perceptions of physical attractiveness which involves views of what is and is not considered beautiful or attractive.The study of...

.

Many forms of similarity have been shown to increase liking. Similarities in opinions, interpersonal styles, amount of communication skill, demographics, and values have all been shown in experiments to increase liking.

Several explanations have been offered to explain similarity increases interpersonal attraction (like-prefers-like). First, people with similar interests tend to put themselves into similar types of settings. For example, two people interested in literature are likely to run into each other in the library and form a relationship (involving the propinquity effect). Another explanation is that we notice similar people, expect them to like us, and initiate relationships. Also, having relationships with similar people helps to validate the values held in common. Finally, people tend to make negative assumptions about those who disagree with them on fundamental issues, and hence feel repulsion.