Internally augmented displays: contingent aftereffects as performance aids

Previous research on visual contingent aftereffects has been concerned with examining the effects of various parameters (e.g., spatial frequency and luminance) on the adaptation to, and decay of, contingent aftereffects. The current study tested the viability of using visual contingent aftereffects in a display context. Using established characteristics of contingent aftereffects, a program of contingent aftereffect adaptation was designed. Studies were conducted to determine if subjects who were adapted to see visual contingent aftereffects invoked by a visual display could achieve more rapid or certain identification of a display under low luminance conditions. The results confirmed (a) that contingent aftereffects can improve performance on a visual discrimination task requiring information from a display and (b) that contingent aftereffects are more enhanced at low levels of illumination.     

Adaptive coordination and alignment of eye and hand

Under spatial misalignment of eye and hand induced by laterally displacing prisms (11.4 degrees in the rightward direction), subjects pointed 60 times (once every 3 s) at a visually implicit target (straight ahead of nose, Experiment 1) or a visually explicit target (an objectively straight-ahead target, Experiment 2). For different groups in each experiment, the hand became visible early in the sagittal pointing movement (early visual feedback). Adaptation to the optical misalignment during exposure (direct effects) was rapid, especially with early feedback; complete compensation for the misalignment was achieved within about 30 trials, and overcompensation occurred in later trials, especially with an explicit target. In contrast, adaptation measured with the misalignment removed and without visual feedback after blocks of 10 pointing trials (aftereffects) was slow to develop, especially with delayed feedback and an implicit target; at most, about 40% compensation for the misalignment occurred after 60 trials. This difference between direct effects and aftereffects is discussed in terms of separable adaptive mechanisms that are activated by different error signals. Adaptive coordination is activated by error feedback and involves centrally located, strategically flexible, short-latency processes to correct for sudden changes in operational precision that normally occur with short-term changes in coordination tasks. Adaptive alignment is activated automatically by spatial discordance between misaligned systems and involves distributed, long-latency processes to correct for slowly developing shifts in alignment among perceptual-motor components that normally occur with long-term drift. The sudden onset of misalignment in experimental situations activates both mechanisms in a complex and not always cooperative manner, which may produce overcompensatory behavior during exposure (i.e., direct effects) and which may limit long-term alignment (i.e., aftereffects).     

Curvature-specific color aftereffects

Adaptation to convex and concave arcs in different colored light results in curvature-specific color aftereffects when arcs are later viewed in white light. In three experiments, it was shown that these color aftereffects often are partial (restricted to limited regions of the test arcs) rather than uniform, and in addition that aftereffects induced by exposure to arcs transfer to straight-line displays of particular orientation, and vice versa. These data were interpreted as evidence that arcs are processed in the visual system in relation to the orientations of local straight line approximations instead of on a global basis. In these terms, curvature-specific color aftereffects are merely complex forms of the orientation-specific color aftereffects first described by McCollough (1965).     

Effects of spatial filtering and lack of effects of visual imagery on pattern-contingent color aftereffects

Checkerboards contain fundamental two-dimensional Fourier components oriented 45° from the edges of individual checks. Previous studies have shown that contingent color aftereffects following adaptation to chromatic checkerboard stimuli were associated with the fundamental components rather than the edges, In the present experiments, we measured contingent color aftereffects, using the method of constant stimuli, after subjects adapted to unfiltered checkerboards and checkerboards with the fundamental Fourier components removed. The adaptation stimuli were magenta (or green) squares and green (or magenta) diamonds; the test stimuli were vertical or oblique sine-wave gratings with different saturations, After adaptation to unfiltered checkerboards, aftereffects contingent on the fundamental components were obtained. In contrast, after adaptation to filtered stimuli, aftereffects of smaller magnitude were found to be aligned with the edges. The data support the previous findings of spatial-frequency-contingent color after-effects with checkerboard adaptation stimuli and indicate that the aftereffects can be associated with edges if the fundamental components of adaptation stimuli are removed by spatial filtering. We reexamined the possibility of color aftereffects induced by imagery of checkerboards. Contrary to the previous reports, no significant aftereffects were obtained.     

Two auditory aftereffects and their dependency on carrier frequency

It is suggested that aftereffects caused by swept change of sound level (Reinhardt-Rutland & Anstis, Note 1) may contribute to auditory motion aftereffects (Grantham & Wightman, 1979). The latter appear to show selectivity for frequency; they are substantial if the frequency is .5 kHz but not if it is 2 kHz. An experiment was carried out to show to what extent there is such selectivity for aftereffects from swept sound-level change; this showed that they are substantial over a much wider range of frequencies than auditory motion aftereffects. It is concluded that the frequency selectivity of auditory motion aftereffects might be explained by frequency selectivity for inter-aural phase differences.     

Orientation-specific luminance aftereffects

Prolonged viewing of bright vertical (horizontal) gratings alternating with dim horizontal (vertical) gratings generates negative brightness aftereffects that are contingent on the orientation of orthogonal test gratings. The effect is measured by a brightness cancellation technique, similar to the color cancellation technique used in measuring McCollough effects. Like the latter, brightness aftereffects appear to persist for long periods. The magnitude of these aftereffects is a positive monotonic function of the luminance difference between the inducing gratings, and it depends on the conditions of induction; monocular induction generates larger aftereffects than binocular induction does. The aftereffect transfers interocularly, although its magnitude in the contralateral eye is substantially attenuated; binocular measurement, following monocular induction, results in even smaller aftereffects. An attempt to understand these findings within the computational model of brightness perception developed by Grossberg and Mingolla (1985a, 1985b) is presented.     

Buildup and decay of a three-dimensional rotational aftereffect obtained with a three-dimensional figure

Gaps in past literature have raised questions regarding the kinds of stimuli that can lead to three-dimensional (3-D) rotation aftereffects. Further, the characteristics of the buildup and decay of such aftereffects are not clear. In the present experiments, rotation aftereffects were generated by projections of cube-like stimuli whose dynamic perspective motions gave rise to the perception of rotation in unambiguous directions; test stimuli consisted of similar cubes whose rotation directions were ambiguous. In experiment 1, the duration of the adaptation stimulus was varied and it was found that the 3-D rotation aftereffect develops with a time constant of approximately 26 s. In experiment 2, the duration between adaptation and testing was varied. It was found that the 3-D rotation aftereffect has a decay constant of about 9 s, similar to that observed with 2-D motion aftereffects. Experiment 3 showed that the rotation aftereffects were not simple depth aftereffects. To account for these aftereffects and related data, a modification of an existing neural-network model is suggested.     

Awareness becomes necessary between adaptive pattern coding of open and closed curvatures

Visual pattern processing becomes increasingly complex along the ventral pathway, from the low-level coding of local orientation in the primary visual cortex to the high-level coding of face identity in temporal visual areas. Previous research using pattern aftereffects as a psychophysical tool to measure activation of adaptive feature coding has suggested that awareness is relatively unimportant for the coding of orientation, but awareness is crucial for the coding of face identity. We investigated where along the ventral visual pathway awareness becomes crucial for pattern coding. Monoptic masking, which interferes with neural spiking activity in low-level processing while preserving awareness of the adaptor, eliminated open-curvature aftereffects but preserved closed-curvature aftereffects. In contrast, dichoptic masking, which spares spiking activity in low-level processing while wiping out awareness, preserved open-curvature aftereffects but eliminated closed-curvature aftereffects. This double dissociation suggests that adaptive coding of open and closed curvatures straddles the divide between weakly and strongly awareness-dependent pattern coding.     

Generalization of prism adaptation

Prism exposure produces 2 kinds of adaptive response. Recalibration is ordinary strategic remapping of spatially coded movement commands to rapidly reduce performance error. Realignment is the extraordinary process of transforming spatial maps to bring the origins of coordinate systems into correspondence. Realignment occurs when spatial discordance signals noncorrespondence between spatial maps. In Experiment 1, generalization of recalibration aftereffects from prism exposure to postexposure depended upon the similarity of target pointing limb postures. Realignment aftereffects generalized to the spatial maps involved in exposure. In Experiment 2, the 2 kinds of aftereffects were measured for 3 test positions, one of which was the exposure training position. Recalibration aftereffects generalized nonlinearly, while realignment aftereffects generalized linearly, replicating Bedford (1989, 1993a) using a more familiar prism adaptation paradigm. Recalibration and realignment require methods for distinguishing their relative contribution to prism adaptation.     

Effective luminance contrast as a parameter in contingent aftereffects

Variation in the magnitude of contingent aftereffects was explored as a function of the luminance contrast ratio profile of inspection stimuli. Positive contrast stimuli (chromatic bars interspersed with achromatically brighter bars) produced substantially attenuated aftereffects compared with negative contrast stimuli (chromatic and dark bars). This attenuation was hypothesized to result from retinal image deterioration of positive contrast gratings due to retinal reflection/scatter. In a second experiment, subjects selected for their light retinal pigmentation manifested substantial enhancement of the asymmetry between the aftereffects generated by positive and negative contrast gratings. Those with dark fundus pigmentation showed symmetrical aftereffects.     

Prism exposure aftereffects and direct effects for different movement and feedback times

The effects of movement time and time to visual feedback (feedback time) on prism exposure aftereffects and direct effects were studied. In Experiment 1, the participants' (N = 60) pointing limb became visible early in the movement (.2-s feedback time), and eye-head aftereffects increased with increasing movement time (.5 to 3.0 s), but larger hand-head aftereffects showed little change. Direct effects (terminal error during exposure) showed near-perfect compensation for the prismatic displacement (11.4 diopters) when movement time was short but decreasing compensation with longer movement times. In Experiment 2, participants' (N = 48) eye-head aftereffects increased and their larger hand-head aftereffects decreased with increasing movement time (2.0 and 3.0 s), especially when feedback time increased (.25 and 1.5 s). Direct effects showed increasing overcompensation for longer movement and feedback times. Those results suggest that aftereffects and direct effects measure distinct adaptive processes, namely, spatial realignment and strategic control, respectively. Differences in movement and feedback times evoke different eye-hand coordination strategies and consequent direct effects. Realignment aftereffects also depend upon the coordination strategy deployed, but not all strategies support realignment. Moreover, realignment is transparent to strategic control and, when added to strategic correction, may produce nonadaptive performance.     

The role of temporal delay and repeated prospective memory cue exposure on the deactivation of completed intentions

Previous studies have shown that completed prospective memory (PM) intentions entail aftereffects in terms of ongoing-task-performance decrements in trials containing repeated PM cues which previously served as PM cues triggering the intended action. Previous research reported that PM aftereffects decrease over time, thus revealing a specific time course of PM aftereffects. In the present study, we tested two accounts for this pattern, assuming either that the decline of aftereffects is related to the temporal distance to PM task completion or may be a result of the repeated exposure of repeated PM cues in the ongoing task. In three experiments, we manipulated both the temporal distance to PM task completion and the frequency of repeated PM cues and demonstrated that aftereffects of completed intentions declined with repeated exposure of formerly relevant PM cues. In addition, effects of repeated exposure were not only limited to the repetition of specific PM-cue exemplars but also generalized to other semantically related PM cues within the PM-cue category. Together, findings show that decreased aftereffects of completed intentions are not related to the temporal duration of the subsequent test block, but crucially depend on the repeated exposure of the previously relevant PM cues.     

Prism Exposure Aftereffects and Direct Effects for Different Movement and Feedback Times

The effects of movement time and time to visual feedback (feedback time) on prism exposure aftereffects and direct effects were studied. In Experiment 1, the participants' (N = 60) pointing limb became visible early in the movement (.2-s feedback time, and eye-head aftereffects increased with increasing movement time (.5 to 3.0 s), but larger hand-head aftereffects showed little change. Direct effects (terminal error during exposure) showed near-perfect compensation for the prismatic displacement (11.4 diopters) when movement time was short but decreasing compensation with longer movement times. In Experiment 2, participants' (N = 48) eye-head aftereffects increased and their larger hand-head aftereffects decreased with increasing movement time (2.0 and 3.0 s), especially when feedback time increased (.25 and 1.5 s). Direct effects showed increasing overcompensation for longer movement and feedback times. Those results suggest that aftereffects and direct effects measure distinct adaptive processes, namely, spatial realignment and strategic control, respectively. Differences in movement and feedback times evoke different eye -hand coordination strategies and consequent direct effects. Realignment aftereffects also depend upon the coordination strategy deployed, but not all strategies support realignment. Moreover, realignment is transparent to strategic control and, when added to strategic correction, may produce nonadaptive performance.     

Prism adaptation in left-handers

Two experiments with left-handers examined the features of prism adaptation established by previous research with right-handers. Regardless of handedness, (1) rapid adaptation occurs in exposure pointing with developing error in the opposite direction after target achievement, especially with early visual feedback in target pointing; (2) proprioceptive or visual aftereffects are larger, depending on whether visual feedback is available early or late, respectively, in target pointing; (3) the sum of these aftereffects is equal to the total aftereffect for the eye-hand coordination loop; (4) intermanual transfer of visual aftereffects occurs only for the dominant hand; and (5) visual aftereffects are larger in left space when the dominant hand is exposed to leftward displacement. A notable handedness difference is that, while transfer of proprioceptive aftereffects only occurs to the nondominant hand in right-handers, transfer occurs in both directions for left-handers, but regardless of handedness, such transfer only occurs when the exposed hand is tested first after exposure. A discussion then focuses on the implications of these data for a theory of handedness.     

Simple and contingent aftereffects of perceived duration in vision and audition

After repeated presentations of a long inspection tone (800 or 1,000 msec), a test tone of intermediate duration (600 msec) appeared shorter than it would otherwise appear. A short inspection tone (200 or 400 msec) tended to increase the apparent length of the intermediate test tone. Thus, a negative aftereffect of perceived auditory duration occurred, and a similar aftereffect occurred in the visual modality. These aftereffects, each involving a single sensory dimension, aresimple aftereffects. The following procedures producedcontingent aftereffects of perceived duration. A pair of lights, the first short and the second long, was presented repeatedly during an inspection period. When a pair of test lights of intermediate duration was then presented, the first member of the pair appeared longer in relation to the second. A similar aftereffect occurred in the auditory modality. In these latter aftereffects, the perceived duration of a test light or tone is contingent—dependent—on its temporal order, first or second, within a pair of test stimuli. An experiment designed to test the possibility of cross-modal transfer of contingent aftereffects between audition and vision found no significant cross-modal aftereffects.     

Perceptual asymmetries associated with changing-loudness aftereffects

Listening to decreasing sound level leads to an increasing-loudness aftereffect, whereas listening to increasing sound level leads to a decreasing-loudness aftereffect. Measuring the aftereffects by nulling them in short test stimuli reveals that increasing-loudness aftereffects are greater than decreasing-loudness aftereffects. However, this perceptual asymmetry may be due to another illusion--the growing-louder effect: In the absence of any adaptation, short steady stimuli are heard as growing louder. In an experiment in which the duration of test stimuli varied from 1.0 to 2.5 sec, the growing-louder effect did not occur in the longer test stimuli, but the asymmetry in changing-loudness aftereffects remained. The aftereffect asymmetry is therefore independent of the growing-louder effect. The aftereffect asymmetry is consistent with other psychophysical and physiological evidence that is believed to concern potential collision: An approaching sound-source elicits increasing sound level. In addition, the aftereffect asymmetry parallels a well-known asymmetry regarding aftereffects of visual motion, which is also attributed to potential collision.     

前瞻记忆意向后效应的年龄差异

前瞻记忆意向后效应会对日常生活产生负面影响,研究发现这种现象在老年人中尤其突出。近些年来,研究者们从内外两方面对影响前瞻记忆意向后效应年龄差异的因素进行了探讨,了解到认知老化所带来的抑制能力的衰退以及短时记忆缺陷是造成其年龄差异的主要原因。未来研究需进一步拓展对认知老化的机制和抑制控制能力的认识。另外,可以采用事件相关电位（Event-Related Potentials, ERPs）和功能性磁共振成像（Functional Magnetic Resonance Imaging, fMRI）等脑成像技术揭示前瞻记忆意向后效应年龄差异的加工机制及神经机制。     

Spatial frequency content of visual imagery

Three experiments employing the McCollough paradigm were conducted to determine the spatial-frequency content of visual imagery. In Experiment 1, large and reliable pattern-contingent color aftereffects were obtained after adaptation to visual imagery. The direction of the aftereffects indicated that subjects were adapting to higher spatial frequencies in their imagery. These results contrast with the data of Experiment 2, which demonstrate that color aftereffects obtained with adaptation to physically present stimuli are mediated by the fundamental spatial frequency components. The magnitude of the imagery-induced aftereffects in Experiment 1 equaled the magnitude of the externally induced aftereffects obtained in Experiment 2 with the same subjects. By blurring the to-be-imaged patterns (Experiment 3), the fundamental Fourier components became the salient perceptual features of the stimuli, and the direction of the imagery-induced aftereffects was reversed from that of Experiment 1, indicating that the spatial frequency content of the imagery had changed from higher to lower frequencies. Under normal viewing conditions, subjects use the higher spatial frequencies associated with the perceptually salient edges of stimuli to construct their images. The results of Experiments 1 and 3 are discussed in light of a current controversy over the nature of information representation in imagery, and it is concluded that support has been obtained for the analog model of visual imagery.     

Effects of situational cues on prism-induced aftereffects

A test was made of the hypothesis that external stimuli present during exposure to lateral displacement of the visual field can serve as situational cues whose presence or absence will influence the magnitude of aftereffects manifested subsequent to adaptation resulting from the exposure. The results indicated that the relative aftereffects were significantly greater when thenondisplacing goggles were worn during the periods in which aftereffect measurements were taken than was the case when they were removed during these test periods. The finding that manipulation of certain cues, i.e., the restriction of the visual field, weight, etc., of the goggles, associated with the adaptation period can in part determine the size of observed aftereffects provides evidence in support of the notion that aftereffects can be conditioned to precisely given constellations of stimuli In addition, the need for caution in conceptualizing aftereffects as simply the persistence of adaptive shifts once visual displacement has been terminated is suggested.