The visual accommodation response during concurrent mental activity

Concurrent mental activity seems to be a significant, nonvisual factor affecting the human accommodation response. Two experiments were conducted to determine the direction and magnitude of this accommodation response. Experiment 1 employed a concurrent, written backwards counting task. Experiment 2 employed a concurrent, mental imagery task of “thinking near” and “thinking far.” In both experiments, the concurrent secondary task effected a cumulative accommodative shift toward the visual far point of from .25 to .75 diopter away from a near (3.0 diopter) target. This accommodative shift was observed only in the presence of a stimulus field and not in open-loop (analogous to empty-field) conditions. In addition, a long-term instability in the open-loop method of obtaining the dark focus was observed. Similarities between this accommodative shift and the pupillary response are noted. The accommodation response is discussed in relationship to both an attention-sharing and an involuntary autonomic response model.     

The contribution of visual persistence to the perceived duration of brief targets

Two experiments were conducted to examine the role of sensory persistence on tasks of perceived duration employing very brief visual stimuli. Using a standard temporal judgment task, the first experiment replicated both the “size effect” and “empty-filled” illusion reported by previous investigators. However, entirely comparable results were also found with a probematching task, which theoretically assesses the degree of persistence exhibited by a stimulus. The second experiment examined the effect of target luminance on perceived duration. Consistent with a sensory persistence interpretation, judgments of duration increased with increasing luminance. The results from the two experiments were discussed in terms of varying degrees of retinal persistence produced by different stimuli. This view was contrasted with currently dominant interpretations that postulate changes in perceived duration to reflect different information-processing requirements across stimulus conditions.     

The effects of spatial frequency and target type on perceived duration

Two experiments are reported that attempt to demonstrate a critical role played by sensory persistence on a standard perceived-duration task employing brief visual stimuli. Experiment 1 examined the effect on perceived duration of varying the spatial frequency of a target. For both 40- and 70-msec flashes, increased spatial frequency resulted in reduced estimates of perceived duration. These results were contrasted with predictions derived from cognitive processing models of duration perception. In Experiment 2, three typical types of target employed in current research (an outlined circle, a “noise”-filled circle, and a completely filled circle) were shown to differ significantly in their perceived duration and in their sensitivity to increases in physical duration. The results were discussed in terms of variable degrees of retinal persistence produced by the three types of targets. The possible implications for specific discrepancies in the literature and across-study comparisons in general were enumerated.     

Monaural localization: An analysis of practice effects

Four listeners (experimental group) received one trial a session for 60 sessions on a monaural localization task in which six loudspeakers, positioned 15 deg apart, were placed on the side of the functioning ear. Four additional listeners (control group) received 60 massed trials first and then one trial a session for 60 sessions. The stimulus consisted of a single train of five high-frequency pulses. An ANOVA conducted on the 60 trials distributed over sessions showed that the experimental group’s performance was significantly inferior to that of the control group. Members of the former continued to displace sounds toward the open ear throughout the entire test. Those of the control group exhibited this tendency, but to a much lesser extent. The experience of locating 60 massed trials clearly had a robust effect on subsequent performance. We contend that, by virtue of presenting only one trial a session, the magnitude of the massed-trial effect was little attenuated by our tests to measure it. We interpret our substantive finding to mean that during the 60 massed trials, the control group formed a perceptual representation of the auditory space which served it well when placed on the one-trial-a-session regimen. Those in the experimental group were unable to develop an adequate representation of the auditory space, presumably because their monaural localization experience was restricted to only one trial a session.     

Dynamic visual noise and the stereophenomenon: Interocular time delays,depth, and coherent velocities

Attention, Perception, & Psychophysics - This study concerns the stereophenomenon obtained with binocular viewing of dynamic visual noise with a neutral density filter over one eye. Such a...     

The effects of delayed and displaced visual feedback on motor control

Developments in television technology have made possible new approaches to the study of the role of visual feedback in motor control. In two experiments using a special videodisc recording and playback system, the effects of delaying for 66 msec a subject's view of his own hand during a target-directed movement was investigated. The observed effects of such visually delayed feedback compared to spatially distorted feedback produced by prisms led to three major conclusions: (a) despite the behavioral similarity (overshooting) induced by the two kinds of altered feedback, the role of each in the visual-motor control loop is different; (b) adaptation to and the after effect of the two kinds of altered feedback are based on different control mechanisms (c) the processing and use of visual information in hand control requires less time than previous experiments have indicated.     

Soteriological dimensions in the work of Heinz Kohut

A framework of theological inquiry is utilized to illuminate soteriological dimensions implicit in Heinz Kohut's psychology of the self as expressed in his most recent work,The Restoration of the Self. Kohut's new formulations involve the unfolding of a saving approach that through its broad application seeks to overcome “the psychological danger that puts the psychological survival of modern Western man into the greatest jeopardy.” The theological inquiry employed asks: What is the essential nature of man? How has man fallen away from his essential self? By what means is he to be saved from his broken condition? Kohut's implicit and explicit “answers” are summarized by dealing with four cardinal issues in his book: definitions of the self: the relationship of a psychology of the self to other psychologies; theory concerning the selfs structure, development, and restoration; and the centrality of the empathic response.     

Teacher reactions to school-based consultation services: A multivariate analysis

The impact of consultation services on teachers' preferences for consultation versus referral approaches and upon teachers' perceptions of severity for common acting out, withdrawal, and academic types of student problems were investigated. The subjects were 96 teachers whose public and parochial schools were matched and randomly assigned to treatment and control groups. Following a 14-week period during which advanced school psychology graduate students served as consultants in the treatment schools, the Pupil Problem Behavior Inventory (PPBI) was administered to all teachers. The results of a repeated measures MANOVA analysis indicated that the teachers in the treatment group rated the acting out and academic problems on the PPBI as significantly less severe than did teachers in the control group. The subjects in both the treatment and control groups indicated a significant preference for consultation rather than referral services for all types of student problems presented in the PPBI. There was a moderate, positive correlation between perceived problem severity and teacher preference for referral rather than consultation services. The study's results were interpreted as supportive of the consultation model.     

Processing of information about location during locomotion: Effects of a concurrent task and locomotion patterns

How maintenance of orientation during locomotion in unfamiliar environments is accomplished was investigated by having subjects walk behind a moving light line (1.12 m/sec) in a dark room and, from a stopping point, numerically estimate direction and distance to the starting point. Two linear distances (5.0–8.4 m) and the angle of direction change (45, 90, and 135 deg) were orthogonally varied as 12 locomotion patterns. Eight high-school students were assigned to each of three conditions, two in which the starting point was invisible, one in which it was visible. In one of the former conditions the subjects counted backwards rapidly during walking. Lower accuracy and longer latency times were found in the counting condition whilst the other two conditions differed only slightly. The results suggested that accurate maintenance of orientation is achieved by recurrent encoding, coordination and decoding of information about direction change and locomotion distance, processes which demand central processing capacity and therefore are interfered with by a concurrent task.