Effects of instructions and drug administration on temporal resolution of paired flashes

Sixteen male alcoholics were shown pairs of light flashes separated by intervals ranging from 0 to 100 msec., and judged whether there were one or two flashes. Two-flash fusion theshold (TFT) was raised by administration of promazine hydrochloride, a tranquilizing drug, and was higher for strict than for lenient instructions. Signal detection analysis showed that the drug reduced sensitivity but did not affect criterion, while instructions altered criterion placement without changing sensitivity.     

Discrimination of spatial and temporal intervals defined by three light flashes: Effects of spacing on temporal judgments and of timing on spatial judgments

Observers were presented stimulus patterns consisting of a sequence of three laterally displaced light flashes, which defined two spatial intervals and two temporal intervals. The position and time of the second flash were varied factorially, and observers were asked to make relative judgments of either the two spatial intervals or the two temporal intervals. “Induction” effects of stimulus timing on spatial judgments and of stimulus spacing on temporal judgments were both found; however, the directionality of these effects differed between subjects. The results are inconsistent with the hypothesis, derived from previous findings, that such effects are determined primarily by a tendency toward perceiving constant velocity of apparent motion; it is proposed that the directionality of the induction effects is determined largely by the strategy adopted by the observer for combining spatial and temporal stimulus information.     

An aftereffect to discrete stimuli producing apparent movement and succession

After observing the sequential flashing of two lights that produced either the perception of apparent movement or the perception of the succession of two stationary lights, the presentation of the lights in the opposite direction produced the perception of a more rapid apparent movement or of a more rapid succession of the light flashes. These aftereffects suggest the presence of neural structures for the discrimination of sequential changes in spatial position which are subject to adaptation and respond with decreased sensitivity to the repetitive presentation of the two lights in a given spatial direction. The results are interpreted to support the hypothesis that the perception of apparent movement involves the excitation of specific neural mechanisms selectively responsive to sequential changes in stimulus position. An alternative hypothesis is that the perception of apparent movement involves an inference based on the separate registrations of the position of a stimulus at one point in time and the position of that stimulus at an earlier point in time.     

Transient spatial attention degrades temporal resolution

To better understand the interplay between the temporal and spatial components of visual perception, we studied the effects of transient spatial attention on temporal resolution. Given that spatial attention sharpens spatial resolution, can it also affect temporal resolution? To assess temporal resolution, we measured the two-flash fusion threshold When two flashes of light are presented successively to the same location, the two-flash fusion threshold is the minimal interval between the flashes at which they are still perceived as two flashes, rather than a single flash. This assessment of temporal resolution was combined with peripheral precuing--a direct manipulation of transient spatial attention. This allowed us to demonstrate, for the first time, that spatial attention can indeed affect temporal resolution. However, in contrast to its effect on spatial resolution, spatial attention degrades temporal resolution. Two attentional mechanisms that could account for both attentional effects--enhanced spatial resolution and reduced temporal resolution--are discussed.     

Automatic visual bias of perceived auditory location

Studies of reactions to audiovisual spatial conflict (alias “ventriloquism”) are generally presented as informing on the processes of intermodal coordination. However, most of the literature has failed to isolate genuine perceptual effects from voluntary postperceptual adjustments. A new approach, based on psychophysical staircases, is applied to the case of the immediate visual bias of auditory localization. Subjects have to judge the apparent origin of stereophonically controlled sound bursts as left or right of a median reference line. Successive trials belong to one of two staircases, starting respectively at extreme left and right locations, and are moved progressively toward the median on the basis of the subjects’ responses. Response reversals occur for locations farther away from center when a central lamp is flashed in synchrony with the bursts than without flashes (Experiment 1), revealing an attraction of the sounds toward the flashes. The effect cannot originate in voluntary postperceptual decision, since the occurrence of response reversal implies that the subject is uncertain concerning the direction of the target sound. The attraction is contingent on sound-flash synchronization, for early response reversals did no longer occur when the inputs from the two modalities were desynchronized (Experiment 2). Taken together, the results show that the visual bias of auditory localization observed repeatedly in less controlled conditions is due partly at least to an automatic attraction of the apparent location of sound by spatially discordant but temporally correlated visual inputs.     

The spatial constraint in intersensory pairing: no role in temporal ventriloquism

A sound presented in temporal proximity to a light can alter the perceived temporal occurrence of that light (temporal ventriloquism). The authors explored whether spatial discordance between the sound and light affects this phenomenon. Participants made temporal order judgments about which of 2 lights appeared first, while they heard sounds before the 1st and after the 2nd light. Sensitivity was higher (i.e., a lower just noticeable difference) when the sound-light interval was approximately 100 ms rather than approximately 0 ms. This temporal ventriloquist effect was unaffected by whether sounds came from the same or a different position as the lights, whether the sounds were static or moved, or whether they came from the same or opposite sides of fixation. Yet, discordant sounds interfered with speeded visual discrimination. These results challenge the view that intersensory interactions in general require spatial correspondence between the stimuli.     

Coordinated flexibility: how initial gaze position modulates eye-hand coordination and reaching

Reaching to targets in space requires the coordination of eye and hand movements. In two experiments, we recorded eye and hand kinematics to examine the role of gaze position at target onset on eye-hand coordination and reaching performance. Experiment 1 showed that with eyes and hand aligned on the same peripheral start location, time lags between eye and hand onsets were small and initiation times were substantially correlated, suggesting simultaneous control and tight eye-hand coupling. With eyes and hand departing from different start locations (gaze aligned with the center of the range of possible target positions), time lags between eye and hand onsets were large and initiation times were largely uncorrelated, suggesting independent control and decoupling of eye and hand movements. Furthermore, initial gaze position strongly mediated manual reaching performance indexed by increments in movement time as a function of target distance. Experiment 2 confirmed the impact of target foveation in modulating the effect of target distance on movement time. Our findings reveal the operation of an overarching, flexible neural control system that tunes the operation and cooperation of saccadic and manual control systems depending on where the eyes look at target onset.     

The aftereffects of ventriloquism: patterns of spatial generalization

We examined how visual recalibration of apparent sound location obtained at a particular location generalizes to untrained locations. Participants pointed toward the origin of tone bursts scattered along the azimuth, before and after repeated exposure to bursts in one particular location, synchronized with point flashes of light a constant distance to their left/right. Adapter tones were presented straight ahead in Experiment 1, and in the left or right periphery in Experiment 2. With both arrangements, different generalization patterns were obtained on the visual distractor's side of the auditory adapter and onthe opposite side. On the distractor side, recalibration generalized following a descending gradient; practically no generalization was observed on the other side. This dependence of generalization patterns on the direction of the discordance imposed during adaptation has not been reported before, perhaps because the experimental designs in use did not allow its observation.     

Driven to distraction? The effect of simulated red light running camera flashes on attention and oculomotor control

Do similar factors influence the allocation of attention in visually sparse and abstract laboratory paradigms and complex real-world scenes? To explore this question we conducted a series of experiments that examined whether the flash that accompanies a Red Light Running Camera (RLRC) can capture observers' attention away from important roadway changes. Inhibition of Return (IOR) and eye movement direction served as indices of the spatial allocation of attention. In two experiments, participants were slower to respond to the brake lights of a vehicle in a driving scene when an RLRC flash occurred nearby or were slower to initiate eye movements to brake light signals (IOR effects). In a third experiment, we found evidence that less prevalent RLRC flashes disrupted eye movement control. Results suggest that attention can be misdirected as a result of RLRC flashes and provide additional evidence that findings from simple laboratory paradigms can predict the allocation of attention in complex settings that are more familiar to observers.     

Perception of moving, sounding objects by four-month-old infants

Infants and adults were presented with two moving objects accompanied by a single percussive sound. In different experiments, the sound occurred when one object moved through a particular spatial position, when it abruptly changed its direction of movement, or when it made contact with a rigid surface. Infants responded to the sound-object relationship whenever the sound occurred as the object changed direction, irrespective of its impacts with the surface. Adults, in contrast, responded to the sound-object relationship most clearly when sounds were synchronized with impacts. In infancy, perception of auditory-visual relationships thus depends in part on detection of discontinuities in the movement of a visible object.     

Does spatial information impact immediate verbatim recall of verbal navigation instructions?

The present study addresses the issue of whether spatial information impacts immediate verbatim recall of verbal navigation instructions. Subjects heard messages instructing them to move within a two-dimensional depiction of a three-dimensional space consisting of four stacked grids displayed on a computer screen. They repeated the instructions orally and then followed them manually by clicking with a mouse on the grids. Two groups with identical instructions were compared; they differed only in whether the starting position was indicated before or after the instructions were given and repeated, with no differences in the manual movements to be made. Accuracy on both the oral repetition and manual movement responses was significantly higher when the starting position was indicated before the instructions. The results are consistent with the proposal that there is only a single amodal mental representation, rather than distinct verbal and nonverbal representations, of navigation instructions. The advantage for the before condition was found even for the oral repetition responses, implying that the creation of the amodal representation occurred immediately, while the instructions were being held in working memory. In practical terms, the findings imply that being able to form a mental representation of the movement path while being given verbal navigation instructions should substantially facilitate memory for the instructions and execution of them.     

对想象环境的空间更新

学界传统上将空间更新定义为个体随着身体运动对其所处真实环境空间表征的自动更新过程, 然而近年来有研究发现个体还可以对想象环境进行空间更新, 但其机制尚不明确。本研究实验1被试站在场景内学习物体空间位置之后, 保持学习朝向直线走到测试位置。其中, 0度组保持学习朝向站立, 180度组原地转动180度, 面对学习朝向的相反方向站立。两组被试均想象自己仍然站在学习位置, 面对学习朝向。然后被试旋转90度, 从3个想象朝向(记忆一致朝向、感觉运动一致朝向和不一致朝向)完成空间判断任务。结果发现0度组记忆一致朝向和感觉运动一致朝向成绩均优于不一致朝向, 而180度组无此优势。实验2被试从学习空间移动到测试空间过程中被迷向, 其他条件与实验1的180度组相同。但是, 实验2被试在记忆一致朝向和感觉运动一致朝向的成绩均优于不一致朝向。结果证明人们可以通过对在线空间表征进行想象平移或将离线记忆与空间更新系统相联结两种方式, 对想象环境进行空间更新。     

Is position "special" in visual attention? Evidence that top-down processes guide visual selection.

The role of spatial position in selective visual processing has been the source of recent debate. Experiments by Tsal and Lavie (1988) and van der Heijden et al. (1996) have been designed to establish the status of position in visual selection. Tsal and Lavie found that observers tend to select letters from a briefly presented array according to position. Using the same paradigm, van der Heijden et al. found that observers tend to select according to colour, except under conditions of low contrast and unrestricted eye movements. The present study attempted to reconcile these findings by exploring the influence of top-down processes (task instructions) while explicitly controlling for eye movements. Experiment 1 demonstrated there was no inherent selection bias for stimuli similar to those used by van der Heijden et al., suggesting that the tendency to select according to colour found by van der Heijden et al. was due to task demands. Experiment 2 further established the role of top-down factors by replicating the results of van der Heijden et al. with our stimuli. Experiment 3 demonstrated that selection can be switched from colour to position by changing the demands of the task. These results suggest that selection may be accounted for by task demands (e.g., instructions) with no priority access for position information.     

Cross-modal detection using various temporal and spatial configurations

To better understand temporal and spatial cross-modal interactions, two signal detection experiments were conducted in which an auditory target was sometimes accompanied by an irrelevant flash of light. In the first, a psychometric function for detecting a unisensory auditory target in varying signal-to-noise ratios (SNRs) was derived. Then auditory target detection was measured while an irrelevant light was presented with light/sound stimulus onset asynchronies (SOAs) between 0 and ±700 ms. When the light preceded the sound by 100 ms or was coincident, target detection (d') improved for low SNR conditions. In contrast, for larger SOAs (350 and 700 ms), the behavioral gain resulted from a change in both d' and response criterion (β). However, when the light followed the sound, performance changed little. In the second experiment, observers detected multimodal target sounds at eccentricities of ±8°, and ±24°. Sensitivity benefits occurred at both locations, with a larger change at the more peripheral location. Thus, both temporal and spatial factors affect signal detection measures, effectively parsing sensory and decision-making processes.     

Audiovisual tau effect

This study investigated how spatial intervals between successive visual flashes are influenced by the temporal intervals between auditory pure tones presented concurrently with the flashes. Three successive visual flashes defined two spatial intervals with different extents as well as two equal temporal intervals. The onsets of the first and third tones were temporally aligned with those of the first and third flashes, while the onset of the second tone was temporally offset to that of the second visual flash, resulting in shorter or longer temporal intervals between pairs of tones. Observers judged which of the first or second spatial intervals between flashes was shorter. The results showed that the shorter temporal interval between tones caused underestimation of the spatial interval between flashes. On the other hand, stimuli without the first and third tones did not result in underestimation of spatial intervals between flashes. These results indicate an audiovisual tau effect, which is triggered by a constant velocity assumption applied to moving objects defined by more than one modality.     

The extraretinal signal for the visual perception of direction

The dependence of the perception of direction on two kinds of extraretinal signals was measured by asking Ss to indicate the position of a fixation target relative to the subjective straight ahead. Outflow was studied by making such localizations while the fixating eye was loaded by means of weights attached to a suction contact lens. Inflow was studied by making such localizations with brief test flashes to a passively rotated eye while the other eye fixated. Shifts in the perceived direction, of the fixation target were in line with predictions from outflow theory and not influenced by conflicting inflow signals.     

Orientation and lever responding in auditory discriminations in squirrel monkeys.

Head orientation during auditory discriminations was studies in squirrel monkeys using a two-lever trial-by-trial procedure. Animals were studied using auditory discriminations based on the position of the sound and on the spectral content differences between a pure tone and a noise. After the percentage of correct responses reached asymptote, head orientation was measured using videotape recordings. Orientation occurred on virtually every trial and was under the control of the position of the sound under all conditions. Lever responding was controlled by the same parameters of the sound under some conditions, and by different parameters in others. Orientation and lever responding were correlated (a level response could be predicted from the direction of orientation) when both responses were under the control of the same parameters of the sound. The two responses were uncorrelated when they were controlled by different parameters of the sound. Orientation and lever responding were not functionally related.     

Crossmodal spatial attention shift produced by centrally presented gaze cues1

Abstract: Despite previous failures to identify visual‐upon‐auditory spatial‐cuing effects, recent studies have demonstrated that the abrupt onset of a lateralized visual stimulus triggers a shift of spatial attention in response to auditory judgment. Nevertheless, whether a centrally presented visual stimulus orients auditory attention remained unclear. The present study investigated whether centrally presented gaze cues trigger a reflexive shift of attention in response to auditory judgment. Participants fixated on a schematic face in which the eyes looked left or right (the cue). A target sound was then presented to the left or right of the cue. Participants judged the direction of the target as quickly as possible. Even though participants were told that the gaze direction did not predict the direction of the target, the response time was significantly faster when the gaze was in the target direction than when it was in the non‐target direction. These findings provide initial evidence for visual‐upon‐auditory spatial‐cuing effects produced by centrally presented cues, suggesting that a reflexive crossmodal shift of attention does occur with a centrally presented visual stimulus.     

Exploring the Construct Validity of the Social Cognition and Object Relations Scale in a Clinical Sample

The resistance of the Personal Orientation Dimensions (POD) to deliberate attempts at creating a favorable impression was investigated. Two groups of college students were used: (a) 21 students completed the POD under standard instructions, then received information about actualization, and completed the POD again under instructions to Create a very good impression; (b) 21 students completed the POD under standard instructions, then received information not related to actualization, and completed the POD again under instructions to create a very good impression. An analyses indicated that providing students with information about actualization did not facilitate their ability to create a favorable impression on the POD. The POD profiles produced by both groups changed significantly, and in a similar direction from pretest to posttest. Evidence is presented suggesting the existence of a "lie profile" which distinguishes deliberate attempts to create a favorable impression on the POD. These findings provide support for the resistance of the POD to deliberate attempts at creating a favorable impression.     

The fakability of the personal orientation dimensions: evidence for a lie profile

The resistance of the Personal Orientation Dimensions (POD) to deliberate attempts at creating a favorable impression was investigated. Two groups of college students were used: (a) 21 students completed the POD under standard instructions, then received information about actualization, and completed the POD again under instructions to Create a very good impression; (b) 21 students completed the POD under standard instructions, then received information not related to actualization, and completed the POD again under instructions to create a very good impression. An analyses indicated that providing students with information about actualization did not facilitate their ability to create a favorable impression on the POD. The POD profiles produced by both groups changed significantly, and in a similar direction from pretest to posttest. Evidence is presented suggesting the existence of a "lie profile" which distinguishes deliberate attempts to create a favorable impression on the POD. These findings provide support for the resistance of the POD to deliberate attempts at creating a favorable impression.