Dissociation between visual attention and visual mental imagery

Visual mental imagery (which involves creating, interpreting, and transforming visual mental representations, i.e., "seeing with the mind's eye") and visual attention typically are described as distinct processes. However, some researchers have claimed that imagery effects can be explained by appeal to attention (and thus, that imagery is nothing more than a form of attention). In this study, we used a size manipulation to demonstrate that imagery and attention are distinct processes. We reasoned that if participants are asked to perform each function (imagery and attention) using stimuli of two different sizes (large and small), and that stimulus size affects the two functions differently, then we could conclude that imagery and attention are distinct cognitive processes. Our analyses showed that participants performed the imagery task better when stimuli were large, whereas they performed the attention task better when stimuli were small. This finding demonstrates that imagery and attention are distinct cognitive processes.