Hunting for individual differences in cognitive processes: Verbal ability and semantic processing of pictures and words

Semantic category decisions were examined for single picture and word stimuli. Consistent with previous research, pictures yielded faster latencies than words and both showed significant taxonomic frequency effects for positive decisions. The results are interpreted in terms of general models for semantic verification, in which both pictures and words involve access to the same underlying semantic knowledge base. The latter conclusion was supported by correlation-regression analyses on individual item latencies. Variations in processing latency as a function of stimulus mode, taxonomic frequency, and type of decision were analyzed with respect to adult individual differences in verbal ability, The results uniformly failed to show a significant relationship between verbal ability and any processing speed measure. The lack of any significant relationship is discussed in light of previous results on verbal ability and processing speed, suggesting obvious qualifications of past results and possible reinterpretations of the meaning of previously obtained speed differences.