The homogeneity effect in counting

Abstract

In Experiment 1, college students counted digits presented in one row. In the homogeneous condition, the digits were identical to one another; in the heterogeneous condition the digits were different. Homogeneous rows of digits were counted more slowly and less accurately. In Experiments 2 and 3, this "homogeneity" effect remained when a space was inserted between each digit, when a heterogeneous border was put around the digits, and when subjects used a finger to count each digit one by one. However, the homogeneity effect was eliminated when the digits were presented on three different levels. Presenting the digits on three levels also improved counting in the heterogeneous condition. These results are consistent with the hypothesis that the Gestalt principles of grouping can act preattentively against the process of isolating each object to be counted. © 1987 Psychonomic Society, Inc.