School of Psychology
How has our understanding of similarity changed since Tversky (1977)? How can recent theories of how conceptual knowledge is organised accommodate this change?
The idea of similarity and our understanding of the processes that are involved in identifying similar objects has changed over the years. Similarity is defined as the state or fact of being similar and in psychological terms refers to the psychological degree of identifying two mental representations.
Similarity is based on three properties which are perceptual, functional and biological features. These properties allow for categorization to occur when objects are considered to be similar as they ensure that both the object and the environment in which it is found are known. Categorization enables individuals to make predications based on the known functions of the object and the properties that it may contain.
Similarity is also broken into two different concepts, one being taxonomic relations which are based on shared features (for example dog bear) and the second is thematic relations which are based on co-occurrence in events or scenarios known as a schema (for example dog toy). These two processes are explored in this essay and why they are critical for categorization and allow individuals to make similarity judgements.
During this essay we will start with discussing some early work from the 1970s by Tversky (1977) who explores a single process theory towards similarity judgement. Leading on from this some experimental papers such as Lin and Murphy (2001) and a similarity model proposed by Yeh and Barsalou (2006) will be discussed and how they have changed our understanding of similarity by proposing the idea of a dual process.
As stated, we will start by discussing the contrast model proposed by Tversky (1977) based on featural approaches that assumes individuals represent concepts by lists of features that describe properties of an item. His theory used the idea of feature comparison when making similarity judgements and shared features were known as commonalities. It was believed that objects with more commonalities would be rated as being more similar. He proposed a model that showed objects being represented by sets of features and that similarity judgements were based on matching features alone, therefore stating that similarity must be a linear process. This led individuals to believe that similarity judgements are derived by a single taxonomic process, however more recent theories and models have argued against this and propose a dual process is required.
An example of the proposed idea of a dual process came from Wisniewski and Bassok (1999). Tverskys idea of feature comparison was considered as an important part of how individuals make similarity judgement, however this paper investigated the possibility of a second process that occurs after the initial comparison. It was believed that co-occurrence of specific obje...