The relationship between self-reported vividness and latency during mental size scaling of everyday items: phenomenological evidence of different types of imagery

We examined how the relationship between ratings of vividness (or image strength) and image latency might reflect the concerted action of two visual imagery pathways hypothesized by Kosslyn (1994): the ventral pathway, processing object properties, and the dorsal pathway, processing locative properties of mental images. Participants formed their images at small or large angular display sizes, varying the amount of size scaling needed. In Experiment 1, display size varied between participants, and images were trial unique. The higher the vividness, the faster the generation of small images (requiring size scaling of less than 10 degrees), which would recruit mainly the ventral pathway. This vivid-is-fast relationship changed for large images (requiring size scaling of 10 degrees or more), which would recruit mainly the dorsal pathway. The size-dependent alteration of the vivid-is-fast relationship was replicated in the first block of Experiment 2. However, when repeated over 3 consecutive blocks, image generation sped up, and gradually the vivid-is-fast relationship tended to occur for all display sizes until complete automatization of image generation occurred. The findings suggest that differential patterns of vividness-latency relationship can reflect the types of images involved, their relative ventral and dorsal contributions, and the involvement of working memory.