The temporal stability of cluster and switch scores using a modified COWAT procedure

This study examined the impact of instructional changes on the temporal stability of cluster and switch scores for the Controlled Oral Word Association Test [COWAT; Benton, A. L., Hamsher, K., & Sivan, A. B. (1994). Multilingual Aphasia Examination (3rd ed.). Iowa City, IA: AJA Associates]. Healthy undergraduates were assigned randomly into experimental (N = 60) and control (N = 60) groups. Experimental group participants were administered three letters as customary, then informed about clustering strategies prior to completing three additional letters. Control group participants received the original instructions only for all six letters. All participants were examined on two separate occasions. The mean inter-assessment interval was 38.6 days (ranging from 29 to 47 days). Stability coefficients for cluster and switch scores on the last set of letters differed significantly between groups, as higher coefficients were observed for the experimental group. In contrast, stability coefficients for the total words produced and mean cluster size did not differ between groups. Although the temporal stability improved, the resulting coefficients were modest (e.g., r(icc) = .76 for clusters; r(icc) = .79 for switches). We present implications of these findings and considerations for future research.