Pictures are typically better remembered than words, but explanations for this fact diverge. Some attribute picture superiority to more distinctive perceptual qualities, others to more efficient conceptual processing. In an effort to separate perceptual and conceptual factors, two groups were presented with mixed lists of pictures and words and were subsequently tested for recognition in either the original or the opposite (picture/word) format. One group, the Format Inclusion group, was instructed to endorse both formats of a studied item; the other - the Format Exclusion group - was instructed to endorse only the original format. Multinomial models were fitted to the response data, with separate parameters for a high-threshold process, recognizing items of high familiarity, and a low-threshold process, rejecting items of low familiarity. Model testing showed that both conceptual and perceptual processing was more efficient for pictures than for words. Especially the low-threshold process showed dramatic picture superiority.