The influence of valence and motivation dimensions of affective states on attentional breadth and the attentional blink.

Affective state has been shown to affect attention, but the affective dimension responsible for attentional effects remains under debate. Some studies suggest that attentional effects depend on the valence dimension of the affective state. Others have proposed that attentional effects depend on the motivational intensity of the affective state. We tested the effect of induced affective states on the attentional blink and attentional breadth. In separate conditions, we induced four affective states with different combinations of valence (positive vs. negative) and motivational intensity (low vs. high). We used an RSVP digit identification task to measure the attentional blink and used the local-global visual processing task to measure attentional breadth. For both tasks, affective pictures were presented before each trial to induce the intended affective state. In Experiment 1, the affective pictures were chosen to have similar average arousal across conditions, whereas in Experiment 2, arousal was allowed to covary with expected motivational intensity. Contrary to previous findings, we found no evidence that affective state influenced either the attentional blink or attention breadth. We found no detectable differences between conditions with positive or negative induced affect, nor between affective state conditions with low or high motivational intensity. For attentional blink, the size of the possible effects was at most a 2-3% change in detection rate. Our results suggest that either the affective induction method is not reliably effective, or there is not a direct relationship between the valence or motivational intensity of affective state and the distribution of attention. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Perception of object motion during self-motion: Correlated biases in judgments of heading direction and object motion.

This study investigated the relationship between perceived heading direction and perceived motion of an independently moving object during self-motion. Using a dual task paradigm, we tested whether object motion judgments showed biases consistent with heading perception, both across conditions and from trial to trial. Subjects viewed simulated self-motion and estimated their heading direction (Experiment 1), or walked toward a target in virtual reality with conflicting physical and visual cues (Experiment 2). During self-motion, an independently moving object briefly appeared, with varied horizontal velocity, and observers judged whether the object was moving leftward or rightward. In Experiment 1, heading estimates showed an expected center bias, and object motion judgments showed corresponding biases. Trial-to-trial variations were also correlated: on trials with a more rightward heading bias, object motion judgments were consistent with a more rightward heading, and vice versa. In Experiment 2, we estimated the relative weighting of visual and physical cues in control of walking and object motion judgments. Both were strongly influenced by nonvisual cues, with less weighting for object motion (86% vs. 63%). There were also trial-to-trial correlations between biases in walking direction and object motion judgments. The results provide evidence that shared mechanisms contribute to heading perception and perception of object motion.

Non-spatial similarity can bias spatial distances in a cognitive map.

The cognitive map theory suggests the hippocampal-entorhinal system has a representation of space that encodes geometric properties. There is also evidence that the hippocampus plays a critical role in supporting declarative memory, and recent theories have hypothesized the mechanism for encoding space is the same as that for processing memory. If space is not represented independently, it might be influenced by non-spatial properties. This study tested whether connections between non-spatial properties can distort judgments about spatial distance. In virtual reality, subjects navigated through an environment to learn the locations of target houses, and then were tested on their ability to judge the pairwise distances between houses and reconstruct a map of the environment. The environment was constructed to have pairs of houses with the same spatial distance but either the same or different color. If memory for spatial and non-spatial properties interact, similar houses would be expected to be judged as closer. In Experiment 1, the similar pairs all had the same color, while in Experiment 2, each pair had a different color to make the pairs more distinctive. We observed that similar houses were drawn closer on reconstructed maps in both experiments, and pairwise distance judgments were smaller for similar houses in Experiment 2. Biases from color similarity are difficult to reconcile with independent representation of space. Our results support theories that space is represented with other properties, and the mechanisms for encoding space in the hippocampal-entorhinal system have a broader function.

The experience of stereoblindness does not improve use of texture for slant perception.

Stereopsis is an important depth cue for normal people, but a subset of people suffer from stereoblindness and cannot use binocular disparity as a cue to depth. Does this experience of stereoblindness modulate use of other depth cues? We investigated this question by comparing perception of 3D slant from texture for stereoblind people and stereo-normal people. Subjects performed slant discrimination and slant estimation tasks using both monocular and binocular stimuli. We found that two groups had comparable ability to discriminate slant from texture information and showed similar mappings between texture information and slant perception (biased perception toward frontal surface with texture information indicating low slants). The results suggest that the experience of stereoblindness did not change the use of texture information for slant perception. In addition, we found that stereoblind people benefitted from binocular viewing in the slant estimation task, despite their inability to use binocular disparity information. These findings are generally consistent with the optimal cue combination model of slant perception.

Dual processes underlie the effect of the Ebbinghaüs illusion on control of grasping.

Previous studies have shown that control of grasping is affected by the Ebbinghaüs illusion. However, there is debate about whether effects on grasping are solely due to the illusion or involve other processes. The aim of this study was to distinguish the influences of the size illusion and obstacle avoidance on control of grip aperture. We compared size perception and grip aperture during grasping for targets in Ebbinghaüs contexts that varied in the size, distance and density of flankers. The size illusion is affected by all of these flanker parameters, while effects due to obstacle avoidance would depend primarily on flanker-target distance. We found that flanker size had consistent effects on perceptual estimation and grip control during grasping: larger flankers caused the target to appear smaller, and the maximum grip aperture (MGA) during grasping was reduced. However, the effects of flanker-target distance were more complicated. Increasing flanker-target distance generally caused the target to appear smaller but this effect became weaker with sparse flankers. For grip control, the flanker-target distance effect had opposite directions in two flanker density conditions: Increasing flanker-target distance caused MGA to decrease with dense flankers and to increase with sparse flankers. These findings can be explained by a combination of influences from size illusion and obstacle avoidance on grasping. Our results do not support that visuomotor control is immune to visual illusions, such as the Ebbinghaüs illusion. Apparent discrepancies between perception and visuomotor control with visual illusions could be explained by additional influence of obstacle avoidance mechanisms. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Different generalization of fast and slow visuomotor adaptation across locomotion and pointing tasks.

Sensorimotor adaptation can involve multiple learning processes with different time courses, and these processes may have different patterns of transfer. In this study, we tested how slow learning and fast learning transfer across tasks, and the specificity of transfer. We tested two natural goal-directed tasks: pointing and walking toward a visible target. We also tested a novel "hand locomotion" task in which subjects used pointing movements to cause simulated self-motion in virtual reality. The hand locomotion task used the same physical movement as pointing, but performed the same function as stepping. During an experimental block, subjects performed alternating training trials with perturbed visual feedback and test trials with no feedback. The test trials were either the same task to measure adaptation, or a different task to measure transfer. Perturbations on adaptation trials varied over time as a sum of sinusoids with different frequencies. Fast learning would be expected to produce equal responses to fast and slow perturbations, while slower learning would dampen responses to higher frequency perturbations. Subjects were generally not aware of the smoothly varying perturbations, but showed detectable adaptation for all three tasks. Only pointing produced significantly different responses to high- and low-frequency perturbations, consistent with slow learning. Adaptation of pointing produced more transfer to the hand locomotion task, which shared the same effector and motor actions, than to the stepping task. The other tasks showed fast learning but little or no slow learning, and equal transfer to tasks with different effector or function. Our results suggest that the slower components of sensorimotor adaptation are more movement specific, while faster learning is more generalizable.

Multiple texture cues are integrated for perception of 3D slant from texture.

The projected image of a textured surface contains multiple texture cues to three-dimensional (3D) surface orientation. Previous studies have reported conflicting findings about the roles of various texture cues. We tested the influence of texture compression relative to other texture cues using a cue conflict paradigm. Observers viewed images of textured planar surfaces with varied slants (0°-70°) and estimated 3D slant by aligning their hand with the virtual surface. Conflicts between texture cues were created by stretching or compression the texture along the surface, which selectively changes the slant specified by texture compression. The texture distortions were relatively small (±10% or ±20%) to limit the size of the cue conflicts. Across three experiments, we varied the field of view (10° vs. 20°), texture regularity (circles vs. Voronoi), and availability of binocular cues. In monocular conditions, slant estimates were strongly affected by texture distortions. Analyses of cue weighting found that texture compression had more influence on slant settings than other texture cues and the relative influence of texture compression decreased with larger field of view and less regular textures. In binocular conditions, we also observed effects of texture distortion, and the influence of texture compression relative to information from stereo and other texture cues increased with slant. Our results provide evidence that texture compression contributes to perceived slant, in addition to other texture cues such as texture scaling. The observed effects of simulated slant, field of view, and texture regularity on cue weighting were all consistent with a model that integrates multiple sources of information according to their reliability.

Perception of 3D slant from textures with and without aligned spectral components.

The image of a textured surface provides multiple potential cues that could be used to perceive its 3D structure. When a surface texture has oriented structure, perspective convergence of the oriented components provides a texture cue, in addition to texture scaling and compression. Some findings suggest that oriented spectral components aligned with the direction of slant are important for 3D perception from texture, but this has only been demonstrated in restricted situations. In this study, we tested the contribution of oriented spectral components for planar surface patches with varied slant (0°-80°) and field of view (16° and 6°). Observers viewed simulated textured surfaces and estimated slant to the perceived surfaces. The simulated textures were octotropic plaids with a full range of orientations, or with either the aligned or perpendicular plaid components removed. We measured perceptual bias in monocular conditions and also the relative weighting of texture and stereo information in binocular conditions. We found that the presence of aligned spectral components did produce some improvement in slant estimates, but the effects were small and only observed in some conditions. There were no detectable differences in texture cue weights. Our results demonstrate that aligned spectral components contribute to perception of slant from texture, but suggest that the contribution is limited when other texture cues are available and informative. Our findings are consistent with the notion that the visual system utilizes multiple sources of texture information for 3D perception.

Automatic adjustments toward unseen visual targets during grasping movements.

We investigated whether control of hand movements can be driven by visual information that is not consciously perceived. Subjects performed reach-to-grasp movements toward 2D virtual objects that were projected onto a rigid surface. On perturbed trials, the target object was briefly presented at a different orientation (±20° rotation) or different size (±20 % scaling) during movement. The perturbed objects were presented for 33 ms, followed by a 200-ms mask and reappearance of the original target object. Subjects perceived only the mask and were not aware of the preceding perturbed stimuli. Unperturbed trials were identical except that there was no change in the target object before the mask. Despite being unaware of the brief perturbed stimuli, subjects showed corrective adjustments to their movements: rotation of the grip axis in response to orientation perturbations, and scaling of grip aperture in response to size perturbations. Responses were detectable 250-300 ms after the perturbation onset and began to reduce 250-300 ms after the reappearance of the original target. Our results demonstrate that the visuomotor system can utilize visual information for control of grasping even when this information is not available for conscious perception. We suggest that this dissociation is due to different temporal resolution of visual processing mechanisms underlying conscious perception and control of actions.

Online processing of shape information for control of grasping.

When picking up objects, we tend to grasp at contact points that minimize slippage and torsion, which depend on the particular shape. Normally, grasp points could be planned before initiating movement. We tested whether grasp points can be determined during online control. Subjects reached to grasp virtual planar objects with varied shapes. On some trials, the object was changed during movement, either rotated by 45° or replaced with a different object. In all conditions, grasp axes were well adapted to the target shape, passing near the center of mass with low force closure angles. On perturbed trials, corrective adjustments were detectable within 320 ms and were toward the same grasp axes observed on unperturbed trials. Perturbations had little effect on either kinematics or the optimality of final grasp points. Our results demonstrate that the visuomotor system is capable of online processing of shape information to determine appropriate contact points for grasping.

Perceptual biases and cue weighting in perception of 3D slant from texture and stereo information.

Multiple cues are typically available for perceiving the 3D slant of surfaces, and slant perception has been used as a test case for investigating cue integration. Previous evidence suggests that texture and stereo slant cues contribute in an optimal Bayesian manner. We tested whether a Bayesian model could also account for perceptual underestimation of slant from texture. One explanation proposed by Todd, Christensen, and Guckes (2010) is that slant from texture is based on an inaccurate optical variable. An alternative Bayesian explanation is that perceptual underestimation is due to the influence of frontal cues and/or a frontal prior, which is weighted according to the reliability of slant cues. We measured slant perception using a hand-alignment task for conditions that provided only texture, only stereo, or combined texture and stereo cues. Slant estimates from monocular texture showed large biases toward frontal, with proportionally more underestimation at low slants than high slants. Slant estimates from stereo alone were more accurate, and adding texture information did not reduce accuracy. These results are consistent with a frontal influence that is decreasingly weighted as slant information becomes more reliable. We also included conditions with small cue conflicts to measure the relative weighting of texture and stereo cues. Consistent with previous studies, texture had a significant effect on slant estimates in binocular conditions, and the relative weighting of texture increased with slant. In some cases, perceived slant from combined stereo and texture cues was higher than from either cue in isolation. Both the perceptual biases and the cue weights were generally consistent with a Bayesian model that optimally integrates texture and stereo slant cues with frontal cues and/or a frontal prior.

Reliability and relative weighting of visual and nonvisual information for perceiving direction of self-motion during walking.

Direction of self-motion during walking is indicated by multiple cues, including optic flow, nonvisual sensory cues, and motor prediction. I measured the reliability of perceived heading from visual and nonvisual cues during walking, and whether cues are weighted in an optimal manner. I used a heading alignment task to measure perceived heading during walking. Observers walked toward a target in a virtual environment with and without global optic flow. The target was simulated to be infinitely far away, so that it did not provide direct feedback about direction of self-motion. Variability in heading direction was low even without optic flow, with average RMS error of 2.4°. Global optic flow reduced variability to 1.9°-2.1°, depending on the structure of the environment. The small amount of variance reduction was consistent with optimal use of visual information. The relative contribution of visual and nonvisual information was also measured using cue conflict conditions. Optic flow specified a conflicting heading direction (±5°), and bias in walking direction was used to infer relative weighting. Visual feedback influenced heading direction by 16%-34% depending on scene structure, with more effect with dense motion parallax. The weighting of visual feedback was close to the predictions of an optimal integration model given the observed variability measures.

Symmetry facilitates shape constancy for smoothly curved 3D objects.

We tested whether the presence of symmetry improves shape discrimination across changes in viewpoint and lighting for smoothly curved 3D objects. We constructed symmetric and asymmetric versions of random 3D shapes by manipulating their spherical harmonic representations. Matched objects had the same power spectra and appear highly similar except for the presence of symmetry. Observers discriminated sequentially presented pairs of either symmetric or asymmetric objects. Objects were presented in conditions that provided different 3D cues: shading only, stereo only, and combined shading and stereo. To control for 2D cues, standard and test objects had matched boundary contours and were rendered with different light sources. Test objects were also rotated in depth by variable amounts (0° to 60°). Across all viewpoint and 3D cue conditions, we found that shape discrimination for symmetric objects was better than for asymmetric objects. The symmetry benefit was not limited to monocular viewing or to conditions with large rotations in depth. In a second experiment, we blocked trials by viewpoint rotation to eliminate uncertainty in object orientation. This improved performance for asymmetric objects relative to symmetric objects, suggesting that symmetry contributes by providing a cue to object orientation. However, a symmetry advantage was still observed in all shape cue conditions, so this was not the sole source of benefit. Our results demonstrate that symmetry improves shape constancy for smooth 3D objects and suggest that one role of symmetry is to provide a reference orientation for an object.

Stereo improves 3D shape discrimination even when rich monocular shape cues are available.

We measured the ability to discriminate 3D shapes across changes in viewpoint and illumination based on rich monocular 3D information and tested whether the addition of stereo information improves shape constancy. Stimuli were images of smoothly curved, random 3D objects. Objects were presented in three viewing conditions that provided different 3D information: shading-only, stereo-only, and combined shading and stereo. Observers performed shape discrimination judgments for sequentially presented objects that differed in orientation by rotation of 0°-60° in depth. We found that rotation in depth markedly impaired discrimination performance in all viewing conditions, as evidenced by reduced sensitivity (d') and increased bias toward judging same shapes as different. We also observed a consistent benefit from stereo, both in conditions with and without change in viewpoint. Results were similar for objects with purely Lambertian reflectance and shiny objects with a large specular component. Our results demonstrate that shape perception for random 3D objects is highly viewpoint-dependent and that stereo improves shape discrimination even when rich monocular shape cues are available.

Can observers judge future circular path relative to a target from retinal flow?

We investigated the ability of observers to judge whether they will pass left or right of a visible target from simulated motion along a circular path. Strategies based on optic flow would generally require compensation for pursuit eye movements. J. P. Wann and D. K. Swapp (2000) proposed an alternative strategy that requires only retinal flow. The experiments compared three conditions that provide the same retinal flow but different observer-relative optic flow. In the heading-relative view condition, simulated view direction rotated with change in heading, as naturally occurs when driving a car. In target-relative view condition, simulated view direction rotated to keep the direction of the target constant. In world-relative view condition, the simulated view direction was fixed relative to the environment. If an observer fixates the target, these conditions produce the same retinal flow. The initial heading direction of simulated motion was varied across trials, and responses were used to compute PSEs representing perceptual bias. Judgments were most accurate in the heading-relative condition. In the target-relative and world-relative view conditions, PSEs indicated large biases consistent with underestimation of path curvature. The large biases suggest that retinal flow is not sufficient to judge future circular path relative to a target.

Adaptation to conflicting visual and physical heading directions during walking.

We investigated the role of global optic flow for visual-motor adaptation of walking direction. In an immersive virtual environment, observers walked to a circular target lying on either a homogeneous ground plane (target-motion condition) or a textured ground plane (ground-flow condition). During adaptation trials, we changed the mapping from physical to visual space to create a conflict between physical and visual heading directions. On these trials, the visual heading specified by optic flow deviated from an observer's physical heading by ±10°. This conflict was not noticed by observers but caused them to walk along curved paths to the target. Over the course of 20 adaptation trials, observers adapted to partially compensate for the conflicts, resulting in straighter paths. When the conflicts were removed post-adaptation, observers showed aftereffects in the opposite direction. The amount of adaptation was similar for target-motion and ground-flow conditions (20-25%), with the ground-flow environment producing slightly faster adaptation and larger aftereffects. We conclude that the visual-motor system can rapidly recalibrate the mapping from physical to visual heading and that this adaptation does not strongly depend on full-field optic flow.

View rotation is used to perceive path curvature from optic flow.

In many natural situations like driving a car, path curvature is accompanied by observer rotation. The experiments reported here test whether such view rotation is necessary to perceive path curvature from optic flow. Displays simulated travel on a circular path along a random dot ground plane, with speeds of 4 m/s and curvature of ±2°/s. In the Rotating View condition, the view direction rotated with heading, as in previous studies. In the Non-rotating View condition, displays simulated travel along the same circular paths but without change in view direction. In Experiment 1, observers indicated positions on their perceived future path at various distances. Judgments were consistent with curved paths in the Rotating View condition, while in the Non-rotating View condition, judgments were consistent with straight paths. In Experiment 2, observers reported whether the simulated path was straight, curved leftward, or curved rightward. Judgments were accurate in the Rotating View condition, while in the Non-rotating View condition, curved paths were often reported to be straight, and observers did not reliably distinguish the sign of curvature. In both experiments, observers had difficulty perceiving path curvature from optic flow when it was not accompanied by view rotation.

A Bayesian model for estimating observer translation and rotation from optic flow and extra-retinal input.

We present a Bayesian ideal observer model that estimates observer translation and rotation from optic flow and an extra-retinal eye movement signal. The model assumes a rigid environment and noise in velocity measurements, and that eye movement provides a probabilistic cue for rotation. The model can simulate human heading perception across a range of conditions, including: translation with simulated vs. actual eye rotations, environments with various depth structures, and the presence of independently moving objects.

Recruitment of a novel cue for active control depends on control dynamics.

We investigated how the visual-motor system recruits a novel visual feedback cue for a manual control task. We presented conditions in which an arbitrary cue (color) was coupled with task-relevant feedback (position or velocity), and measured the effect of the novel cue on performance. Participants used a joystick to keep a moving horizontal line centered on a display under velocity or acceleration control dynamics. Participants normally rely primarily on line position feedback for velocity control and line velocity feedback for acceleration control. The novel color cue was coupled with either line position (becoming red as it deviates from center) or line velocity (becoming red as it moves faster). For velocity control, performance error was smaller and response gain was larger when the novel color cue was coupled with line position than when it was coupled with line velocity. Conversely, for acceleration control, performance was better when color was coupled with line velocity than with line position. Our findings show that the visual-motor system can recruit a novel arbitrary cue to improve active control performance, but the effectiveness of the novel cue depends on its relationship to the feedback appropriate for control dynamics.

Both parallelism and orthogonality are used to perceive 3D slant of rectangles from 2D images.

A 2D perspective image of a slanted rectangular object is sufficient for a strong 3D percept. Two computational assumptions that could be used to interpret 3D from images of rectangles are as follows: (1) converging lines in an image are parallel in the world, and (2) skewed angles in an image are orthogonal in the world. For an accurate perspective image of a slanted rectangle, either constraint implies the same 3D interpretation. However, if an image is rescaled, the 3D interpretations based on parallelism and orthogonality generally conflict. We tested the roles of parallelism and orthogonality by measuring perceived depth within scaled perspective images. Stimuli were monocular images of squares, slanted about a horizontal axis, with an elliptical hole. Subjects judged the length-to-width ratio of the holes, which provided a measure of perceived depth along the object. The rotational alignment of squares within their surface plane was varied from 0 degrees (trapezoidal projected contours) to 20 degrees (skewed projected contours). In consistent-cue conditions, images were accurate projections of either a 10 degree- or 20 degree-wide square, with slants of 75 degrees and 62 degrees, respectively. In cue-conflict conditions, images were generated either by magnifying a 10 degrees image to have a projected size of 20 degrees or by minifying a 20 degree image to have a projected size of 10 degrees. For the aligned squares, which do not produce a conflicting skew cue, we found that subjects' judgments depended primarily on projected size and not on the size used to generate the prescaled images. This is consistent with reliance on the convergence cue, corresponding to a parallelism assumption. As squares were rotated away from alignment, producing skewed projected contours, judgments were increasingly determined by the original image size. This is consistent with use of the skew cue, corresponding to an orthogonality assumption. Our results demonstrate that both parallelism and orthogonality constraints are used to perceive depth from linear perspective.