cell.com/current-biology/supplemental/S0960-9822(06)02331-1). In reality, the ball never leaves the hand. The illusion is effected by the use of learned cues that are visible selleck screening library to the observer, including the magician’s hand and arm movements previously associated with a ball toss, and the magician’s gaze directed along the usual path of the ball. The observer’s inferences about environmental properties and events are probabilistically determined (from the associated cues) but the inferences are incorrect. According to the implicit imagery hypothesis, these flawed inferences are nonetheless manifested as imagery

of motion along the expected path. Moreover, this imaginal contribution to perceptual experience is likely to be mediated by top-down activation of directionally selective MT neurons, in a manner analogous to the effects reported by Schlack and Albright (2007). In other cases of implicit imagery, however, such as a cloud that looks like a poodle or a toast that resembles the Virgin

Mary, the imagined component may be robust but it is scarcely confusable find more with the stimulus. A well-documented and experimentally tractable form of this perceptual phenomenon is variously termed “representational momentum” (Freyd, 1987, Kourtzi, 2004 and Senior et al., 2000), “implied motion” (Kourtzi and Kanwisher, 2000, Krekelberg et al., 2003 and Lorteije et al., 2006), or “illusions of locomotion” (Arnheim, 1951), in which a static image drawn from a moving sequence (such as an animal in a predatory pounce) elicits an “impression” of the motion sequence. This phenomenon is the basis of a common technique in painting, well-described since Leonardo (da Vinci, 1989), in which static visual features are employed to

bring a vibrant impression to canvas. Such impressions are ubiquitous, perceptually robust, and nonvolitional (unlike explicit imagery), but they are not confusable with stimulus motion. Evidence nonetheless suggests that they also reflect top-down pictorial recall of motion—the product of associative experience, in which static elements of a motion sequence have been naturally linked with the movement itself (Freyd, 1987). In support next of this view, static implied motion stimuli have been shown to elicit fMRI signals selectively in human areas MT and MST (Kourtzi and Kanwisher, 2000, Lorteije et al., 2006 and Senior et al., 2000). Krekelberg et al. (2003) have discovered similar effects for single neurons in cortical areas MT and MST. What then differentiates cases in which imagery and stimulus are inseparable from cases in which they are distinct? We have already seen that the distinct experiences associated with explicit imagery versus retinal stimulation are linked to activation of anterior versus posterior regions of visual cortex. We hypothesize that the same cortical dissociation can hold for implicit imagery.