Knowledge in perception and illusion

Following Hermann von Helmholtz, who described visual perceptions as unconscious inferences from sensory data and knowledge derived from the past, perceptions are regarded as similar to predictive hypotheses of science, but are psychologically projected into external space and accepted as our most immediate reality. There are increasing discrepancies between perceptions and conceptions with science's advances, which makes it hard to define 'illusion'. Visual illusions can provide evidence of object knowledge and working rules for vision, but only when the phenomena are explained and classified. A tentative classification is presented, in terms of appearances and kinds of causes. The large contribution of knowledge from the past for vision raises the issue: how do we recognize the present, without confusion from the past. This danger is generally avoided as the present is signalled by real-time sensory inputs-perhaps flagged by qualia of consciousness.     

Depression and the illusion of control

24 depressed and 24 nondepressed undergraduates (Beck Depression Inventory) placed bets on a dice game. The throwing of the dice was either under player-control or croupier-control conditions. As predicted, depressed Ss were more confident of success in the croupier-control condition, and nondepressed Ss were more confident of success in the player-control condition. Results support the view that depressed Ss are characterized by a sense of personal incompetence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Frame-of-reference and hierarchical-organisation effects in the rod-and-frame illusion

Two hypotheses proposed as alternatives by Rock--frame of reference and hierarchical organisation of perception--were tested in a series of experiments with the use of the rod-and-frame illusion. This illusion produces errors in the apparent vertical due to the presence of a tilted frame surrounding the test rod. The apparent vertical is shifted in the direction of the frame tilt. When an upright square was added inside the tilted frame, rod-setting errors varied according to the visual characteristics of the display. In the case of a large display presented in the dark (experiment 1), there continued to be large errors in the direction of the outer-square tilt. This finding supports the frame-of-reference hypothesis, which proposes that the orientation of all objects in the visual field is dominated by the most peripheral reference. In the case of a small display presented in a lit environment (experiments 2 and 3), the direction of errors was the opposite. This latter finding was taken to indicate that the rod was set with reference to the perceived tilt of the inner upright square. Thus, according to a hierarchical-organisation hypothesis, the orientation of an object in the visual field is influenced by objects in the immediate surroundings not by outermost reference. Overall, the results confirm the presence of two qualitatively different classes of orientational phenomena: one is concerned with the definition of egocentric coordinates and one with an object-centred visual representation.     

Effect of hypnotic age regression on the magnitude of the Ponzo and Poggendorff illusions.

The magnitudes of the Ponzo and Poggendorff illusions among 10 hypnotically age-regressed undergraduates were typical of normative data obtained from young children. This effect was almost complete for the Ponzo but not as pronounced for the Poggendorff illusion. A control group under task motivation instructions failed to produce comparable results. It appears that age regression facilitates the use or nonuse of visual cues and mechanisms in the manner typical of earlier stages of perceptual development. It is suggested that these illusions may serve as an objective indicator of hypnotic age regression, and that hypnotic age regression may provide a methodological approach to the experimental study of perceptual development. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attentional processing and the subjective contour illusion.

To distinguish between bottom–up and top–down (TD) accounts of subjective contour (SC) perception, the present investigation used a dual-task paradigm to test the relative attentional demands of real SC perception. In the primary task, 16 undergraduates made speeded same–different discriminations of either paired SC forms or their real contour analogs. Half the Ss performed this primary task in conjunction with a 6-digit short-term memory load secondary task. If subjective forms impose a greater limited-capacity processing load than real forms, then the need to share processing capacity with a secondary task was expected to produce a greater increment in RT for subjective relative to real forms. Results indicate that the expected enhanced RT increment for subjective relative to real forms with the addition of a concurrent memory load was limited to same trials. This result implies that the nature of response indicators must be considered in assessing capacity requirements with the sort of dual-task paradigm used in the present investigation. Nevertheless, the fact that the increment in same RT with the addition of a concurrent memory load was greater for subjective relative to real forms accords with expectations derived from the notion that the perception of SCs is more attention-demanding than that of real contours. A comprehensive theory of SC perception will most likely be formulated within the TD perspective of conceptually driven visual information processing. (90 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Induced mood and the illusion of control.

Examined the directionality of the relationship between realism in judging personal control and depression. Depressed and elated mood states were induced transiently in 40 naturally nondepressed and 40 depressed females (Beck Depression Inventory and the Multiple Affect Adjective Check List), and the impact of these transient mood states on susceptibility to the illusion of control was assessed. Naturally nondepressed Ss gave accurate judgments of control while naturally depressed Ss showed an illusion of control and overestimated their impact on an objectively uncontrollable outcome. Mood induction groups showed predicted changes in self-reported affect and a behavioral measure of depression. These results are in contrast to those of L. B. Alloy and L. Y. Abramson (1979). An implication of the present findings may be that therapeutic interventions for depression that successfully remediate depressive symptoms may also increase depressed individuals' susceptibility to the illusion of control. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuroticism and the illusion of mental health.

Comments on the argument by J. Schedler et al (see record 1994-09623-001) that standard mental health scales appear unable to distinguish between genuine mental health and the illusion of mental health created by psychological defenses. It is asserted that Schedler et al misstate the psychometric position and fail to demonstrate the superiority of clinical judgment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Internal clock processes and the filled-duration illusion.

In 3 experiments, the authors compared duration judgments of filled stimuli (tones) with unfilled ones (intervals defined by clicks or gaps in tones). Temporal generalization procedures (Experiment 1) and verbal estimation procedures (Experiments 2 and 3) all showed that subjective durations of the tones were considerably longer than those of unfilled intervals defined either by clicks or gaps, with the unfilled intervals being judged as approximately 55%-65% of the duration of the filled ones when real duration was the same. Analyses derived from the pacemaker-switch-accumulator clock model incorporated into scalar timing theory suggested that the filled/unfilled difference in mean estimates was due to higher pacemaker speed in the former case, although conclusively ruling out alternative interpretations in terms of attention remains difficult. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of the false-memory illusion.

The counterintuitive developmental trend in the Deese-Roediger-McDermott (DRM) illusion (that false-memory responses increase with age) was investigated in learning-disabled and nondisabled children from the 6- to 14-year-old age range. Fuzzy-trace theory predicts that because there are qualitative differences in how younger versus older children and disabled versus nondisabled children connect meaning information across the words on DRM lists, certain key effects that are observed in adult studies will be absent in young children and in learning-disabled children. Data on 6 such adult effects (list strength, recall inflation, delayed inflation, delayed stability, thematic intrusion, and true-false dissociation) were used to investigate this hypothesis, and the resulting data were consistent with prediction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Size illusion, distance illusion, and terrestrial passage: Comment on Reed.

Comments on C. F. Reed's (see record 1985-29807-001) terrestrial-passage theory, in which it is assumed that the moon's failure to increase in visual subtense while elevating is accounted for strictly by perceptual distancing. This allows a formal account of the moon distance illusion, but at the expense of a compelling explanation of the moon size illusion. In order to explain the distance illusion, Reed also assumes that all objects, regardless of their perceived altitude, are perceived to start from a common point at the horizon. Several alternative applications of Reed's terrestrial-passage foundation to the actual illusions are suggested. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Duration illusion and auditory grouping in infancy.

Extended previous research on perceptual grouping in infancy (Thorpe, Trehub, Morrongiello, & Bull, 1988). Infants' detection of temporal increments to silent intervals between groups of tones was compared with their detection of comparable silent increments within groups of tones. Ss were presented with standard 6-tone sequences, with the first 3 tones differing from the last 3 in harmonic structure, frequency, or intensity, and contrasting sequences with increments of 80 or 100 ms to the silent interval between the 3rd and 4th tone (XXX OOO, between groups) or between the 4th and 5th tone (XXXO OO, within group). Infants discriminated temporally altered sequences from the standard only when the increments occurred within a group. The authors conclude that perceptual grouping processes are operative in infancy and that infants perceive the silent increments between groups of sounds as longer than identical intervals within a group, as do adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postpartum depression and symbiotic illusion.

Discusses the phenomenon of postpartum depression from a transgenerational perspective. The concept of symbiosis is taken from the mother's point of view as well as from the baby's. Symbiosis is defined as a delusional 2-person fantasy of mutual dependence rather than as a normal phase of development. Analysis of a case of postnatal depression is presented to illustrate the clinical and theoretical implications of this viewpoint and how it was applied in treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deconstructing the McGurk–MacDonald illusion.

Cross-modal illusions such as the McGurk–MacDonald effect have been used to illustrate the automatic, encapsulated nature of multisensory integration. This characterization is based in the widespread assumption that the illusory percept arising from intersensory conflict reflects only the end-product of the multisensory integration process, with the mismatch between the original unisensory events remaining largely hidden from awareness. Here the authors show that when presented with desynchronized audiovisual speech syllables, observers are often able to detect the temporal mismatch while experiencing the McGurk–MacDonald illusion. Thus, contrary to previous assumptions, it seems possible to gain access to information about the individual sensory components of a multisensory (integrated) percept. On the basis of this and similar findings, the authors argue that multisensory integration is a multifaceted process during which different attributes of the (multisensory) object might be bound by different mechanisms and possibly at different times. This proposal contrasts with classic conceptions of multisensory integration as a homogeneous process whereby all the attributes of a multisensory event are treated in a unified manner. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hallucinantion and illusion (author''s transl)

The value of an anaesthetic attachment during the first two postgraduate years is considered under three major headings, the value to the recent graduate, the value to the specialty, and the value to the community. The anaesthetic attachment offers all recent graduates an opportunity to perfect practical skills which should from part of the armamentarium of all doctors, and for some there is the option to acquire the ability to administer a safe anaesthetic. Exposure to the specialty at this time is important for recruitment to the specialist ranks.     

Cochlear implants: selection criteria and shifting borders

Cochlear implants have proven to be effective and reliable in postlingually deaf adults. This is also true for congenitally deaf and perilingually deaf children up to the age of six years. Due to the increasing experience, the improvement of implant technology and the proven reliability the selection criteria are broadened with shifting borders. The main extensions are related to age, additional handicaps, residual hearing and special etiologies of deafness. Increasing evidence shows that very early implantation results in better performance and better hearing and speech development. Near-normal language acquisition can be achieved in children implanted under the age of four. Additional handicaps do not automatically exclude a candidate from cochlear implantation. A case-to-case decision has to be made based on additional diagnostics and the experience of the implant centre. A list of suitable handicaps is provided. Severely hearing impaired patients may also be considered for cochlear implantation if their residual hearing provides no benefit for speech discrimination. The same holds true for children. Cochlear implantation in obliterated cochleae and inner ear malformation requires a special surgical technique and special electrode arrays. In this way even difficult cases can be managed with remarkable outcome. Over all, the selection criteria have been broadened with increasing experience and technological improvement. This development may continue and the borderline between hearing aids and cochlear implants will shift further towards severe hearing loss. However, the basis for success still remains good rehabilitation, a team approach and the willingness of the patient to undergo the whole process of cochlear implantation.     

The target in the celestial (moon) illusion.

The visual conditions sufficient to produce the celestial (moon) illusion do not produce it for all presumably suitable celestial targets. For most observers, the illusion is complete for the moon: Apparent visual angle and apparent physical size are inverse functions of elevation, but apparent distance is a direct function. These features of the illusion are attenuated for star clusters and absent for star pairs. Although, in accordance with modern theories of the illusion, the visual terrain may be necessary for the celestial illusion, it is not sufficient; the visual target itself apparently must display particular features. (PsycINFO Database Record (c) 2010 APA, all rights reserved)