Challenging Dual-Coding Theory: Picture Superiority Effects Persist in Aphantasia

Dual-coding theory proposes that superior recall for pictures versus words (picture superiority effect; PSE) and concrete versus abstract words (concreteness effect) results from encoding information both verbally and visually, creating dual memory codes. The current study tested this dual-coding theory by examining recall in individuals with aphantasia, who cannot voluntarily generate mental imagery and thus should not benefit from dual coding. We compared recall performance between aphantasic and typical imagers across four stimulus types: pictures, symbols, concrete words, and abstract words. Contrary to dual-coding predictions, aphantasic individuals showed a robust picture superiority effect. Interestingly, while typical imagers recalled pictures and symbols similarly well, aphantasics recalled symbols significantly better than pictures. These findings challenge dual-coding theory’s explanation of the PSE, indicating that either supplementary image codes are unnecessary for enhanced recall, or dual-coding theory requires substantial revision. Such revision might involve reconsidering that dual codes contribute primarily during encoding rather than retrieval, or broadening the definition of the second code beyond visual imagery—for example, to include motor imagery.