Movement perception in computer-driven visual displays

Computer-driven visual displays (CDVDs), like television and movies, produce stroboscopic rather than continuous physical movement. The success with which the perception of motion is produced depends or. factors such as the fineness of the raster and the temporal and spatiai reiationships of the stimulus points. For a given velocity, the more points there are on the movement trajectory, and the closer their spacing, the better is the perceived movement. Moderately slow retinal velocities (on the order of .4 to .8 deg/sec) produce the highest quality of perceived movement. One can discriminate among possible subclasses of movement detectors by presenting a complex sequence of intensities at two or more points and varying their cross correlation. Motion between two areas can be perceived even when there is zero correlation between the spatial patterns in each location. Perceived motion can be of rotation, as well as of translation. The two-dimensional shadow of a rotating three-dimensional wire figure is perceived as a rotating, rigid, three-dimensional wire figure (the kinetic depth effect). A three-dimensional “shadow” of a hypothetical four-dimensional wire figure also has been produced; it was not seen as rigid.     

Detection of informational constraints related to multi-variate visual displays

A contingent uncertainty of one bit is perceptible when imposed upon a combination of two binary-coded visual display variables, but not when imposed upon a combination of three variables. Why? The limitation may be sought in the average amount of the constraint, in the form of the constraint, or in the particular selection of display variables. Tests were carried out in which apparently equivalent informational constraints were imposed upon a single display variable. Such constraints were highly discriminable. Further tests reveal that the limiting feature for the detection of multi-variate constraints is probably the mean constraint level, averaged over all display elements, rather than the constraint level imposed upon the constrained display elements.     

Selective encoding from multielement visual displays

When a multiletter display is preceded by a bar designating one of the letters for report, reaction time (RT) to voice the indicated letter decreases. Previous research had indicated that the efficiency of this selective mechanism decreases as the number of display elements increases. Two experiments were conducted to determine whether the effect of display size could be eliminated when the indicator precedes the display at long intervals. Results indicated that the display size effect was maintained. The results could not be attributed to eye movements, but were interpreted in terms of a central encoding mechanism that is limited in its precision of localization and exclusion.     

Response inhibition can affect reaction time to abrupt-onset visual displays

Reaction time (RT) to abrupt-onset stimuli has been widely used for more than a century to measure the duration of perceptuo-cognitive and motor processes [Donders, 1868/1969 Attention and Performance II (1969 Acta Psychologica 30 412-431)]. A complicating factor with the RT method is that of response withholding, or response inhibition (RI). The occurrence of RI (under this or other names) has been widely discussed in relation to studies of motor processes but has been largely ignored in relation to studies of perceptuo-cognitive processes. We demonstrate that RI can be a confounding factor when RT to abrupt-onset displays is used to study perceptual and cognitive processes. In experiment 1, new-object targets were more accurately detected than old-object targets in an unspeeded task, but were responded to more slowly in an RT task. Consistent with an interpretation in terms of RI, this pattern of results was dependent on the difficulty of target detection. The data of three further experiments also support predictions from the RI interpretation. It is suggested that RI may be an under-acknowledged factor in RT studies of perceptual and cognitive processes with abrupt-onset displays.     

Undifferentiated facial electromyography responses to dynamic,audio‐visual emotion displays in individuals with autism spectrum disorders

We examined facial electromyography (fEMG) activity to dynamic, audio‐visual emotional displays in individuals with autism spectrum disorders (ASD) and typically developing (TD) individuals. Participants viewed clips of happy, angry, and fearful displays that contained both facial expression and affective prosody while surface electrodes measured corrugator supercilli and zygomaticus major facial muscle activity. Across measures of average and peak activity, the TD group demonstrated emotion‐selective fEMG responding, with greater relative activation of the zygomatic to happy stimuli and greater relative activation of the corrugator to fearful stimuli. In contrast, the ASD group largely showed no significant differences between zygomatic and corrugator activity across these emotions. There were no group differences in the magnitude and timing of fEMG response in the muscle congruent to the stimuli. This evidence that fEMG responses in ASD are undifferentiated with respect to the valence of the stimulus is discussed in light of potential underlying neurobiological mechanisms.     

Automatic attraction of attention to former targets in visual displays of letters

Shiffrin and Schneider (1977, Experiment 4d) reported that after consistent training in search for particular alphanumeric characters, presentation of one of these characters (former targets) as a distractor impeded detection of simultaneously presented current targets. Even if presented in an irrelevant display location, the former target appeared to attract attention. Here, we analyze weaknesses in the design of Experiment 4d and report four follow-up experiments ranging from a fairly close replication of the original multiframe experiment to a rather conventional single-frame search study. In each experiment, presentation of former targets consistently impeded detection of simultaneously presented current targets. The results suggest that automatic attention attraction to individual alphanumeric characters develops not only in the special experimental paradigm used by Shiffrin and Schneider, but also in standard visual search tasks. The fact that attention appeared to be attracted by shapes as complex as individual letters supports the assumption that simultaneously presented visual stimuli can be compared in parallel against memory representations of alphanumeric characters.     

Lateral eye-movement responses to visual stimuli

The association of left lateral eye-movement with emotionality or arousal of affect and of right lateral eye-movement with cognitive/interpretive operations and functions was investigated. Participants were junior and senior students enrolled in an undergraduate course in developmental psychology. There were 37 women and 13 men, ranging from 19 to 45 yr. of age. Using videotaped lateral eye-movements of 50 participants' responses to 15 visually presented stimuli (precategorized as neutral, emotional, or intellectual), content and statistical analyses supported the association between left lateral eye-movement and emotional arousal and between right lateral eye-movement and cognitive functions. Precategorized visual stimuli included items such as a ball (neutral), gun (emotional), and calculator (intellectual). The findings are congruent with existing lateral eye-movement literature and also are additive by using visual stimuli that do not require the explicit response or implicit processing of verbal questioning.     

Convergent and divergent responses to emotional displays of ingroup and outgroup

In the present research, we test the assumption that emotional mimicry and contagion are moderated by group membership. We report two studies using facial electromyography (EMG; Study 1), Facial Action Coding System (FACS; Study 2), and self-reported emotions (Study 2) as dependent measures. As predicted, both studies show that ingroup anger and fear displays were mimicked to a greater extent than outgroup displays of these emotions. The self-report data in Study 2 further showed specific divergent reactions to outgroup anger and fear displays. Outgroup anger evoked fear, and outgroup fear evoked aversion. Interestingly, mimicry increased liking for ingroup models but not for outgroup models. The findings are discussed in terms of the social functions of emotions in group contexts. (PsycINFO Database Record (c) 2011 APA, all rights reserved).     

Discrimination of third-order Markov constraints within visual displays

Discrimination thresholds were measured for third-order Markov constraints within visual displays. The method permits the cancellation of adjacent second-order differences and of first-order differences. Excellent discrimination of third-order constraints is obtained despite the fact that the average conditional repetition probability and the average run length were invariant. The need to distinguish between local short-term and average long-term analyses for the visual system is briefly discussed.     

Perception of two-dimensional Markov constraints within visual displays

A method is described for constructing visual displays in which statistical constraints are encoded within two spatial dimensions without introducing one-dimensional linear constraints. Within each local group of four elements, the state of one element was determined with a given probability by the previously generated states of the other three. Ss rated such displays on a scale from “lumpy” (or crude texture) to “lacy” (or even texture). The consistency of classification obtained for displays with strong aggregated (“lumpy”) properties was substantially higher than that obtained for displays with strong distributed (“lacy”) properties. An incidental feature of the Ss’ behavior was their deliberate degrading of the visual quality of the displays. Comparison is made with one-dimensional displays concatenated in two dimensions.     

A rudimentary touch input device for visual displays

An inexpensive and simple device that can be fitted to existing computer visual display units and that gives a limited touch input capability is described. Small transparent acrylic pieces are held in front of the CRT by stiff wires attached to microswitches. The device has proved useful in the provision of computer-assisted instruction for young children.     

Length distortion of temporally extended visual displays: similarity to haptic spatial perception

Three experiments were designed to investigate length distortion--the tendency to inflate estimates of the inferred distance between two points, as the length of a circuitous pathway between them increases. This phenomenon, previously demonstrated with haptic and locomotor exploration (Lederman, Klatzky, Collins, & Wardell, 1987), was extended to vision through the presentation of pathways as a temporal sequence of illuminated points. The magnitude of the visual effect was less than that previously found in haptics, and conditions promoting the effect included a relatively slow presentation rate and moderately complex pathways. Commonalities in the pattern, if not the magnitude, of length distortion in vision and haptics suggest that similar processes of spatial encoding may underlie the phenomenon in both domains.