Abstract
The linear relation between the time of physically executed movements and the index of difficulty–referred to as Fitts' Law–is also reflected in imagined movements. This evidence supports the hypothesized functional equivalence or corresponding neural substrate that governs executed and imagined movements. As the evidence to date may be attributed to the representation of egocentric efferent and reafferent processes, we aimed to examine the influence of allocentric/relative target information and whether perceived (illusory) environmental context impacts imagery. Fifteen participants executed and imagined reciprocal aiming movements at different indexes of difficulty (4, 5, 6). Adapted from the Ebbinghaus illusion, targets were surrounded by no annuli, large annuli (perceptually small target) or small annuli (perceptually large target). A pre-experimental perceptual target size adjustment task confirmed that participants experienced the perceptual illusion. Temporal measures replicated the significant relation between the index of difficulty with executed (r = .99, p < .00) and imagined (r = .99, p < .00) movement times. There was a significant main effect of illusion (p < 0.05) that revealed shorter times for the control compared to perceptually small and large targets (Fisher's LSD; ps .05). These findings suggest that imagery is equally sensitive to surrounding environmental cues, and thus advocate the role of ecological features during imagery.
