![]() ![]() This pattern of results is broadly consistent with the classic motion aftereffect (Barlow & Hill, 1963), and the authors concluded that the adaptation task had directly changed motion perception. In each case the adaptation phase (static images, or imagined motion) gave rise to a negative aftereffect: participants had an increased probability of judging a (possibly ambiguous) stimulus as having moved in the opposite direction. In both studies participants then judged the motion direction of a dynamic dot stimulus. In a second study (Winawer et al., 2010), participants adapted to a static grating and were asked to imagine that it was moving. ( 2008) had participants adapt to still photographs that implied motion (either leftward or rightward, or inward or outward see Fig. ![]() Such a method offers an empirical approach to determine if high-level cognitions (such as extracted meaning) can filter down to change perception. However, recent research has started revealing aftereffects in which test stimuli are only conceptually related to the adapting stimulus. Aftereffects are also typically constrained to a common sensory dimension, such as when a moving adaptor influences the perceived motion of a test (Barlow & Hill, 1963). the brightness of lights, or the volume, pitch or frequency of a tone see Clifford et al., 2007, for a review). Usually, perceptual aftereffects are quantified by giving people prolonged and repeated exposure to a specific stimulus, and then measuring changes in response to a range of stimulus intensities (e.g. Our results suggest the implied motion aftereffect produces a bias in decision-making, but leaves perceptual processing unchanged.Īn outstanding question in perception research is whether our thoughts, desires, emotions, or cognitions can change how our sensory systems operate. In Experiment 2 (real motion), we find equal changes to decisions and confidence. In Experiment 1 (implied motion), we find support for decision-level changes only, with no change in subjective confidence. ![]() We therefore used subjective confidence as an additional measure of the implied motion aftereffect. Since both categorical decisions and subjective confidence are informed by sensory information, confidence can be informative about whether an aftereffect probably results from changes to perceptual or decision processes. Equally possible, however, is that inferred motion changes decision processes, but not perception. This finding could indicate that inferred motion direction can penetrate sensory processing and change perception. This is termed tactile-kinesthetic aftereffect.Viewing static images depicting movement can result in a motion aftereffect: people tend to categorise direction signals as moving in the opposite direction relative to the implied motion in still photographs. If you pass your hand over a curved surface a number of times and then stroke a straight surface it will appear to be curved in the opposite direction. Aftereffects have been demonstrated in sense modalities other than vision. There is conclusive evidence that figural aftereffects are a function of a brain mechanism rather than a product of activity occurring in the retina: when the first figure is viewed by one eye and the second viewed by the other, the effect is still obtained. The figure then appears to be different because a different part of the brain decodes the message. One theory holds that the brain area which deals with the original stimulus becomes “satiated” or “fatigued” through prolonged inspection, and another area comes into play. Under certain conditions the effects of prolonged exposure to the first stimulus have lasted for several months.Figural aftereffects are not easy to explain. The extent of figural aftereffects increases with the amount of exposure to the first figure, beginning with an exposure of two to five seconds anTEShing a maximum after about one minute. If you stare at a curved line for several moments it will tend to appear less curved than it was at first and if you look at a straight line immediately afterward, it will appear to be curved in the direction opposite to the original curved line (Gibson, 1933). A single experiment will illustrate both of these phenomena. There are two principal types of aftereffect: the apparent distortion of a figure following prolonged inspection, and the effect of inspection of one figure on the perception of a subsequent figure. ![]()
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