The Influence Of The Number Of Stimulus Feature And Feature Saliency On The Exemplar Effects

Categorization is an important cognitive activity. The research of categorization has received abundant results and has become one of the kernel problems in cognitive science. The present study proposes that these different theories can be divided into two categories, one is the rule-based theory and the other is the similarity-based theory. Early research was dominated by the rule-based theory, while recently the similarity-based theory obtained much more experiments' support.However, research of the last ten years has discovered that the interpretation of single representation and single-systerm theory has become weaker not only for the formation of category, but also for the category use. Multiple representation and multiple-systerm theory have been gradually accepted by most people. The rule-based theory and similarity-based theory are developing toward integratation, and some mixture theories and models have appeared.According to exemplar effects, when people decide what a new item is,they are usually affected by the memory of former example seen by them, though they have access to some definite categorization rules. Exemplar effects is a manifestation of interaction between rule and similarity. The existence of exemplar effects shows that the similarity-based process may affect the rule-based process.The research of exemplar effects is still in the initial stage. There are still a lot of arguments about the productive condition and mechanism of exemplar effects.The present study holds that the disadvantage of the former research is that all studies use a five features stimulus, without changing the number of stimulus feature. The present study explores exemplar effects in different perceptual loads conditions by manipulating the number of stimulus feature and feature saliency, in order to investigate categorization process and mechanism more deeply and globly.The present study consist of four experiment researchs. are divided into four studies, which manipulate the number of stimulus feature and feature saliency. Study 1,Study 2,Study 3 and Study 4 explore exemplar effects in the context of balanced stimulus's perceptual feature saliency and stimulus's nonrule-feature perceptual saliency on the rule-based categorization. Study 4 further explores six feature stimulus's exemplar effects with the instruction emphasizing exemplar memory ,in the context of balanced stimulus's perceptual feature saliency and stimulus's nonrule-feature perceptual saliency which manipulate five learning blocks and ten learning blocks.The main results are elaborated as follows.1. Rule-based process and similarity-based process exist in the same categorization task. Exemplar similarity has influence on the use of rule. The nonrule features is necessary to obtain the exemplar effects.2. But these similarity-based mechanisms might be restricted by the different perceptual load made by the number of stimulus feature and perceptual saliency.3. Learning time has influence on the production of exemplar effects on the context of five stimulus features, but it has no influence on the context of four or six stimulus features. This results show that Learning time has influence on exemplar effects and this influence is a very complex mechannism.4.The influence of instruction is restricted by the perceptual load of the present task.