Is suggestion the source of reported visual sensations in perceptual isolation?

The hypothesis that expectation or suggestion is responsible for the reports of visual sensations in perceptual isolation was tested using a control group and 3 additional groups incorporating increasing amounts of verbal and placebo suggestion. Ss were 58 male undergraduates. Prior knowledge and expectations were unrelated to reports of visual sensations. Only the least structured and meaningful type of reported visual sensations was found to increase with suggestion. Other reactions to isolation were unrelated to suggestion. Although the role of direct suggestion in perceptual isolation has been overestimated, the continuous reporting method may be influential in eliciting reports of visual sensations. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The restricting effects of awareness: A paradox and explanation.

Ss were shown tachistoscopically-presented word stimuli to test the distinction between the perceptual processes of registration (what could be called physiological or sensory threshold) and awareness (or the cognitive threshold). The presentation consisted of a stimulus word followed by series of words associated to the stimulus word either in terms of meaning or structural resemblance. Recall of words presented subliminally or supraliminally was facilitated with degree of awareness of actual stimulus word; with greater awareness of the word, associational recall was for words that structurally resembled S word; without awareness, recall was determined by associative meaning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Metrics of visual form.

A review of research work relating perceptual response to physical form parameters. The parameters are classified into transitive, transpositional, and intransitive. The number of intransitive parameters, which comprise measures that specify the characteristics of shape contours proper and contain the bulk of all physical measures, is quite large, but only very recent work has begun to point to the existence of a common denominator of these measures and to the possibility of arriving at a limited set of related and homogeneous parameters based on both empirical evidence and a priori mathematical considerations. (64 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modified Prenatal Sensory Stimulation Influences Postnatal Behavioral and Perceptual Responsiveness in Bobwhite Quail Chicks (Colinus virginianus).

Asynchronous bimodal stimulation during prenatal development elicits higher levels of behavioral and physiological arousal in precocial avian embryos than does unimodal sensory stimulation. To investigate whether the increased arousal associated with prenatal bimodal stimulation has enduring effects into postnatal development, bobwhite quail (Colinus virginianus) embryos received no supplemental stimulation, unimodal auditory stimulation, or bimodal (audiovisual) stimulation prior to hatching. Embryos exposed to concurrent bimodal stimulation demonstrated greater levels of behavioral activity and failed to use maternal visual cues to successfully direct species-specific perceptual preferences following hatching. These results provide initial evidence that asynchronous bimodal sensory stimulation during prenatal development can have enduring effects on early postnatal behavioral arousal and perceptual responsiveness and suggest that developmental limitations on prenatal sensory stimulation play an important role in the emergence of species-typical behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A "pure" measure of perceptual defense uncontaminated by response suppression.

"Using a tachistoscopic recognition technique, an experiment was designed that provided measures both of 'perceptual defense' and of response suppression. The 'perceptual defense' measure could be corrected by the response suppression measure to yield a 'pure' perceptual defense measure. With this method, it was found that Ss scoring high on the Hy scale of the MMPI demonstrate a significant perceptual defense effect over and above a response suppression effect, when confronted by words preselected so as to be emotional for each S individually. It is therefore concluded that perceptual defense effects cannot be accounted for entirely on the basis of response suppression." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sources of reports of visual and auditory sensations in perceptual-isolation experiments.

The review analyzes the experiments on perceptual isolation with special reference to the phenomena of reported visual and auditory sensations. Variables analyzed include: methods of confinement and restriction, conditions of illumination, duration of isolation, set, instructions and suggestions, reporting or verbalization instructions, sleep, S populations, prior knowledge and expectations, intelligence and personality characteristics of Ss, stress response, and methods of obtaining reported visual and auditory sensations. The relevance of some of the findings to physiological, psychoanalytic, cognitive, and social psychological theories of perceptual isolation are discussed. Variables which seem important in the phenomena discussed are set, verbalization instructions, S's alertness, and E's methods of obtaining responses. (2 p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A further study of the relationship between response bias and perceptual defense.

Ss were exposed to tachistoscopically-presented pairs of words and asked to report whether a particular word was on the left or right of a fixation point. A non-statistically-significant trend showed that Ss tended to demonstrate a response bias in terms of reporting anxiety or neutral words on one or the other side whether or not they were in fact on the stated side of the point. A 2nd phase of the experiment presented S with blank stimulus fields although S was expecting words. A response bias was not demonstrated. "… it is suggested that the use of a forced-choice spatial indicator of perception may undermine the motivational basis for perceptual defense." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Practice Increases the Efficiency of Evidence Accumulation in Perceptual Choice.

Most models of choice response time base decisions on evidence accumulated over time. A fundamental distinction among these models concerns whether each piece of evidence is equally weighted (lossless accumulation) or unequally weighted (leaky accumulation). The authors tested a hypothesis derived from A. Heathcote and S. Brown's (2002) self-exciting expert competitor (SEEXC) model of skill acquisition: that evidence accumulation becomes less leaky with practice. The hypothesis was supported by observation that the effects of prime stimuli increased with practice. The authors used metacontrast masked primes, which could not be consciously discriminated by most participants, to avoid methodological problems associated with conscious strategy changes. The form of the law of practice in the data is also shown to be consistent with the SEEXC model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Role of Age and Perceptual Symbols in Language Comprehension.

Older and younger participants read sentences about objects and were then shown a picture of an object that either matched or mismatched the implied shape of the object in the sentence. Participants' response times were recorded when they judged whether the object had been mentioned in the sentence. Responses were faster in the shape-matching condition for all participants, but the mismatch effect was stronger for older than for younger adults, even when the larger variability of the older group's response times was controlled for. These results suggest that older adults may construct stronger situation models than younger adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dilution: A theoretical burden or just load? A reply to Tsal and Benoni (2010).

Load theory of attention proposes that distractor processing is reduced in tasks with high perceptual load that exhaust attentional capacity within task-relevant processing. In contrast, tasks of low perceptual load leave spare capacity that spills over, resulting in the perception of task-irrelevant, potentially distracting stimuli. Tsal and Benoni (2010) find that distractor response competition effects can be reduced under conditions with a high search set size but low perceptual load (due to a singleton color target). They claim that the usual effect of search set size on distractor processing is not due to attentional load but instead attribute this to lower level visual interference. Here, we propose an account for their findings within load theory. We argue that in tasks of low perceptual load but high set size, an irrelevant distractor competes with the search nontargets for remaining capacity. Thus, distractor processing is reduced under conditions in which the search nontargets receive the spillover of capacity instead of the irrelevant distractor. We report a new experiment testing this prediction. Our new results demonstrate that, when peripheral distractor processing is reduced, it is the search nontargets nearest to the target that are perceived instead. Our findings provide new evidence for the spare capacity spillover hypothesis made by load theory and rule out accounts in terms of lower level visual interference (or mere “dilution”) for cases of reduced distractor processing under low load in displays of high set size. We also discuss additional evidence that discounts the viability of Tsal and Benoni's dilution account as an alternative to perceptual load. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The reliability of a response measure: Differential recognition-threshold scores.

In studies of perceptual defense where the dependent variable has been differential thresholds for emotionally toned vs. neutral stimulus materials, little attention has been given to the internal consistency of such measures. A study is reported which suggests that the internal consistency may be very low. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The motivating effects of exteroceptive stimulation.

The effects of perceptual deficit in infancy on the dog are considered insofar as they bear on motivational and emotional problems. "The animal reared in isolation is a permanent screwball at maturity: motivationally, socially, intellectually abnormal." Dog-rearing experiments indicate that "dogs reared in isolation showed none of the physical debility and susceptibility to infection that Spitz reported." Dogs whose patterns of exteroceptive stimulation were restricted were markedly atypical in a number of performances. A finding based on "brainwashing" by Chinese communists in the Korean War is that: "Without physical pain, without drugs, the personality can be badly deformed simply by modifying the perceptual environment." In an experiment with sensory isolation for the human there were hallucinations, disturbances in the selfpercept, impairment of intelligence test performance, changes in EEG, and marked visual disturbances on first emerging from isolation. "With the possible exception of the effects of propaganda, the changes were reversible, disappearing in a day or so." Making isolation more drastic produces motivational and emotional disturbances much more quickly. "Clearly man's motivation is a function of his exteroceptive stimulation." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intersensory redundancy facilitates prenatal perceptual learning in bobwhite quail (Colinus virginianus) embryos.

Information presented redundantly and in temporal synchrony across sensory modalities (intersensory redundancy) selectively recruits attention and facilitates perceptual learning in human infants. This comparative study examined whether intersensory redundancy also facilitates perceptual learning prenatally. The authors assessed quail (Colinus virginianus) embryos' ability to learn a maternal call when it was (a) unimodal, (b) concurrent but asynchronous with patterned light, or (c) redundant and synchronous with patterned light. Chicks' preference for the familiar over a novel maternal call was assessed 24 hr following hatching. Chicks receiving redundant, synchronous stimulation as embryos learned the call 4 times faster than those who received unimodal exposure. Chicks who received asynchronous bimodal stimulation showed no evidence of learning. These results provide the first evidence that embryos are sensitive to redundant, bimodal information and that it can facilitate learning during the prenatal period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the calibration of knowledge and perception

This study examined confidence judgements (i.e., calibration, resolution, and over/underconfidence) and response times in an intellectual knowledge task and a perceptual task requiring location comparisons. At each of four levels of judgement difficulty (i.e., Easy, Hard, Impossible and Misleading/Illusory), very similar properties were evident in the two tasks. The results are inconsistent with theories that assume a fundamentally different basis for confidence in human knowledge and perception.     

The effect of subliminal stimulation upon autonomic and verbal behavior.

Using the subception hypothesis of Lazarus and McCleary, 2 hypotheses pertaining to the effect upon verbal and autonomic behavior of subliminal visual stimulation were tested. The hypotheses stated that: response latencies and GSRs would be determined by the affective value of the stimuli, and the verbal guesses made during subliminal stimulation would be associations to the stimulus items. 7 Ss were used, and after subliminal presentation of the stimuli, each S was presented with his responses and asked to match them against the stimulus items. The part of the hypothesis pertaining to response latencies was not supported, but the part pertaining to GSRs was confirmed. The second hypothesis, likewise, was confirmed. 18 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prenatal experience and postnatal perceptual preferences: Evidence for attentional-bias in bobwhite quail embryos ( Colinus virginianus).

Previous studies have indicated that concurrent multimodal sensory stimulation can interfere with prenatal perceptual learning. This study further examined this issue by exposing 3 groups of bobwhite quail embryos (Colinus virginianus) to (a) no supplemental stimulation, (b) a bobwhite maternal call, or (c) a maternal call paired with a pulsating light in the period prior to hatching. Experiments differed in terms of the types of stimuli presented during postnatal preference tests. Embryos receiving no supplemental stimulation showed no preference between stimulus events in all testing conditions. Embryos receiving exposure to the unimodal maternal call preferred the familiar call over an unfamiliar call regardless of the presence or absence of pulsating light during testing. Embryos exposed to the call-light compound preferred the familiar call only when it was paired with the light during testing. These results suggest that concurrent multimodal stimulation does not interfere with prenatal perceptual learning by overwhelming the young organism's limited attentional capacities. Rather, multimodal stimulation biases what information is attended to during exposure and subsequent testing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An Exemplar Account of the Bow and Set-Size Effects in Absolute Identification.

The extended generalized context model for response times (K. Lamberts, 2000) was designed to account for choice proportions and response times in perceptual categorization. In this article, the hypothesis that the model also offers an account of accuracy and response times in absolute identification was investigated. The model was applied to the data from 2 absolute identification experiments and provided a good account of the bow and the set-size effects in accuracy and response time data from individual participants, including the response time distributions for individual stimuli. The model applications demonstrated that exemplar-based process models offer a viable account of absolute identification data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deterioration and facilitation hypotheses in sensory-deprivation research.

2 opposing hypotheses have emerged from research in sensory deprivation: it impairs mental functioning and it facilitates mental functioning. Much evidence exists for either or both cases, but review of some of the literature suggests that whatever the requirements of the human organism for varied external stimulation, mere reduction or increased patterning of input will not alone produce major disruptive or enhancing effects. The multiplicity of reported results makes it appear unwise to conclude that sensory or perceptual isolation, as it is currently conceived, results in deterioration or facilitation of mental function until more research is accomplished. Evidence from learning studies, in which the disparate hypotheses are most pronounced, stimulated the present attempt to integrate empirically the phenomena reported in a wide range of studies in sensory deprivation. (35 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Is there a mechanism of perceptual defense? A reply to Postman, Bronson, and Gropper.

"The present article is a rebuttal of the point of view expressed in this journal by Postman, Bronson, and Gropper, [see 28: 2283] who criticized the concept of perceptual defense and argued that it is not supported by the experimental evidence. Issue was taken with these authors concerning their understanding of the concept of defense, their espousal of the notion of word frequency as an explanation of perceptual recognition, and the limited variety of studies which they criticize and cite as relevant to the defense concept." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Structural analysis of dreams: Clues to perceptual style.

"… persons who show differences in the perceptual attitude of flexibility-rigidity as estimated from the Rorschach test also differ predictably along this dimension in the perceptual response pattern of their dreams… . Results confirmed the experimental hypothesis." (PsycINFO Database Record (c) 2010 APA, all rights reserved)