shin92: Category size CIRP

shin92R Documentation

Category size CIRP


Category size is the number of examples of a category that have been presented to the participant. The category-size effect (e.g. Homa et al., 1973) is the phenomenon that, as category size increases, the accuracy of generalization to new members of that category also increases. The equal-frequency conditions of Experiment 3 of Shin & Nosofsky (1992) provides the data for this CIRP.




A data frame with the following columns:


Experimental condition (category size). Takes values : 3, 10


Category membership of stimulus. Takes values: 1, 2


Stimulus code, as defined by Shin & Nosofsky (1992). Stimuli beginning 'RN' or 'URN' are the 'novel' stimuli. Stimuli beginning 'P' are prototypes. The remaining stimuli are the 'old' (training) stimuli.


Mean probability, across participants, of responding that the item belongs to category 2.


Wills et al. (2017) discuss the derivation of this CIRP, with Wills et al. (n.d.) providing further details. In brief, the effect has been independently replicated. Experiment 3 of Shin & Nosofsky (1992) was selected due to the availability of a multi-dimensional scaling solution for the stimuli, see shin92train.

Experiment 3 of Shin & Nosofsky (1992) involved the classification of nine-vertex polygon stimuli drawn from two categories. Category size was manipulated between subjects (3 vs. 10 stimuli per category). Participants received eight blocks of training, and three test blocks.

The data are as shown in Table 10 of Shin & Nosofsky (1992). The data are mean response probabilities for each stimulus in the test phase, averaged across test blocks and participants.


Andy J. Wills


Shin, H.J. & Nosofsky, R.M. (1992). Similarity-scaling studies of dot-pattern classification and recognition. Journal of Experimental Psychology: General, 121, 278-304.


Wills et al. (n.d.). Benchmarks for category learning. Manuscript in preparation.

Wills, A.J., O'Connell, G., Edmunds, C.E.R. & Inkster, A.B. (2017). Progress in modeling through distributed collaboration: Concepts, tools, and category-learning examples. The Psychology of Learning and Motivation, 66, 79-115.

See Also

shin92train, shin92oat

catlearn documentation built on March 26, 2022, 1:07 a.m.