Adaptation to displaced vision: Evidence for prolonged after-effects

It was found that brief periods of exposure to visual rearrangement elicit aftereffects that are still of considerable magnitude 24 h later. Despite the existence of these after-effects, visuomotor coordination does not appear to be disrupted between test periods, suggesting that these after-effects may be similar to some of the recently described situation-dependent visual after-effects.     

Adaptation to displaced vision: Amount of optical displacement and practice

The influence of two variables, length of exposure and amount of optical distortion, on adaptation to displaced vision was examined. The extent of adaptation was positively related to number of trials in a task involving spatial localization of a target displaced by a wedge prism. A substantial adaptation (38%) was produced after only two trials. The adaptation was also positively related to degree of optical displacement, except at the highest level used. The findings are discussed in terms of availability of information about the discrepancy between vision and task.     

Allocation of attention and the locus of adaptation to displaced vision.

Experimental subjects were exposed to prism-induced visual displacement of a target whose location was correctly given by proprioceptive-kinesthetic information. Control subjects were exposed alternately to visual displacement or proprioceptive-kinesthetic location information. During the adaptation period, experimental subjects in the visual attention condition performed a localization task that directed them to attend selectively to the visual modality; experimental subjects in the proprioceptive attention condition attended selectively to the proprioceptive modaltiy; control subjects performed the task on the basis of the available modality. Measures of adaptation and aftereffect were secured separately in each of the two modalities. These confirmed the predictions that the shifts in the experimental conditions would be confirmed to localization tests dependent on the unattended modality and that control subjects would not exhibit adaptation. We proposed that allocation of attention determines situational dominance and that dominance determines the locus of adaptation. The findings were compared to those reported by Canon (1970) and were applied to a reassessment of the "visual capture" phenomenon.     

Adaptation to displaced vision: Reafference is a special case of the cue-discrepancy hypothesis

Subjects were exposed to a prismatically displaced view of their actively-moved right hand which was optically “stopped”; they achieved as much adaptation in this condition as in one in which they were allowed full “reafferent” stimulation. This provides further evidence against Held's “reafference“ hypothesis.     

Interocular transfer of orientation-contingent color aftereffects with external and internal adaptation

The issue of whether McCollough effects transfer interocularly was examined in two experiments. In Experiment 1, as in previous experiments, no interocular transfer of McCollough effects was obtained when subjects adapted monocularly to externally present patterns with their unused eyes fully occluded. However, when subjects adapted monocularly (with the unused eye fully occluded) to visual images of those patterns superimposed on physically present chromatic backgrounds, McCollough effects transferred interocularly. In Experiment 2, subjects adapted to either physically present patterns or to images of those patterns (as in Experiment 1), but the unused eye was exposed to unpatterned diffuse white light. In contrast to Experiment 1, the externally adapted subjects showed interocular transfer of McCollough effects. In Experiment 2, the magnitude of the interocular transfer effects produced by imagery was significantly larger than the magnitude of the effects produced by external adaptation, but the magnitude of the imagery-induced aftereffects did not differ from Experiment 1 to Experiment 2. These results extend earlier findings by Kunen and May (1980) and show that McCollough effects can be produced through adaptation to imagery, even though the direction of the imagery-induced aftereffects indicates adaptation to higher spatial frequencies whereas externally derived aftereffects indicate adaptation to lower spatial frequencies. It is concluded that failure of previous studies to obtain interocular transfer of McCollough effects may have resulted from complete occlusion of the contralateral eye. These data point up some interesting similarities and some important differences between imagery and actual vision. The implications for analogical models of visual imagery are discussed.     

Evidence for color-contingent organizational aftereffects

An effort was made to produce negative organizational aftereffects in response to a perceptually ambiguous stimulus that can be seen as a cube in either of two orientations. 6 subjects were adapted to alternative disambiguated versions of the ambiguous cube, shown either in green or magenta light. When tested with the ambiguous figure shown in either green or magenta light, 5 subjects showed negative aftereffects while one subject showed a positive aftereffect. The aftereffects showed an average change in preferred organization of 25%. The results are interpreted in terms of both cognitive and hard-wired processes.     

Spatial-frequency-contingent color aftereffects: Adaptation with one-dimensional stimuli

The McCollough effect was shown to be spatial-frequency selective by Lovegrove and Over (1972) after adaptation with vertical colored square-wave gratings separated by 1 octave. Adaptation with slide-presented red and green vertical square-wave gratings separated by 1 octave failed to produce contingent color aftereffects (CAEs).However, when each of these gratings was adapted alone, strong CAEs were produced. Adaptation with vertical colored sine-wave gratings separated by 1 octave also failed to produce CAEs, but strong effects were produced by adaptation with each grating alone. By varying the spatial frequency of the test sine wave, CAEs were found to be tuned for spatial frequency at 2.85 octaves after adaptation of 4 cycles per degree (cpd) and at 2.30 octaves after adaptation of 8 cpd. Adaptation of both vertical and horizontal sine-wave gratings produced strong CAEs, with bandwidths ranging from 1.96 to 2.90 octaves and with lower adapting contrast producing weaker CAEs. These results indicate that the McCollough effect is more broadly tuned for spatial frequency than are simple adaptation effects.     

Fitting the mind to the world: face adaptation and attractiveness aftereffects

Average faces are attractive, but what is average depends on experience. We examined the effect of brief exposure to consistent facial distortions on what looks normal (average) and what looks attractive. Adaptation to a consistent distortion shifted what looked most normal, and what looked most attractive, toward that distortion. These normality and attractiveness aftereffects occurred when the adapting and test faces differed in orientation by 90° (+45° vs. −45°), suggesting adaptation of high-level neurons whose coding is not strictly retino- topic. Our results suggest that perceptual adaptation can rapidly recalibrate people's preferences to fit the faces they see. The results also suggest that average faces are attractive because of their central location in a distribution of faces (i.e., prototypicality), rather than because of any intrinsic appeal of particular physical characteristics. Recalibration of preferences may have important consequences, given the powerful effects of perceived attractiveness on person perception, mate choice, social interactions, and social outcomes for individuals.     

Spatial-frequency-contingent color aftereffects: Adaptation with two-dimensional stimulus patterns

The spatial-frequency theory of vision has been supported by adaptation studies using checkerboards in which contingent color aftereffects (CAEs) were produced at fundamental frequencies oriented at 45\dg to the edges. A replication of this study failed to produce CAEs at the orientation of either the edges or the fundamentals. Using a computer-generated display, no CAEs were produced by adaptation of a square or an oblique checkerboard. But when one type of checkerboard (4 cpd) was adapted alone, CAEs were produced on the adapted checkerboard and on sine-wave gratings aligned with the fundamental and third harmonics of the checkerboard spectrum. Adaptation of a coarser checkerboard (0.80 cpd) produced CAEs aligned with both the edges and the harmonic frequencies. With checkerboards of both frequencies, CAEs were also found on the other type of checkerboard that had not been adapted. This observation raises problems for any edge-detector theory of vision, because there was no adaptation to edges. It was concluded that spatial-frequency mechanisms are operating at both low- and high-spatial frequencies and that an edge mechanism is operative at lower frequencies. The implications of these results are assessed for other theories of spatial vision.     

Spatial-frequency-contingent color aftereffects: adaptation with one-dimensional stimuli.

The McCollough effect was shown to be spatial-frequency selective by Lovegrove and Over (1972) after adaptation with vertical colored square-wave gratings separated by 1 octave. Adaptation with slide-presented red and green vertical square-wave gratings separated by 1 octave failed to produce contingent color aftereffects (CAEs). However, when each of these gratings was adapted alone, strong CAEs were produced. Adaptation with vertical colored sine-wave gratings separated by 1 octave also failed to produce CAEs, but strong effects were produced by adaptation with each grating alone. By varying the spatial frequency of the test sine wave, CAEs were found to be tuned for spatial frequency at 2.85 octaves after adaptation of 4 cycles per degree (cpd) and at 2.30 octaves after adaptation of 8 cpd. Adaptation of both vertical and horizontal sine-wave gratings produced strong CAEs, with bandwidths ranging from 1.96 to 2.90 octaves and with lower adapting contrast producing weaker CAEs. These results indicate that the McCollough effect is more broadly tuned for spatial frequency than are simple adaptation effects.