Geometrical illusions: study and modelling

The phenomena of geometrical illusions of extent suggest that the metric of a perceived field is different from the metric of a physical stimulus. The present study investigated the Müller-Lyer and Oppel-Kundt illusions as functions of spatial parameters of the figures, and constructed a neurophysiological model. The main idea of the modelling is based on the uncertainty principle, according to which distortions of size relations of certain parts of the stimulus, so-called geometrical illusions, are determined by processes of spatial filtering in the visual system. Qualitative and quantitative agreement was obtained between psychophysical measurement of the strength value of the illusions and the predictions of our model.     

Base rates can affect individual predictions.

356 college students in 4 experiments learned base-rate information and then participated in a predictive social judgment task. In all experiments, predictive behavior was significantly affected by the relevant base rates. In Exp II, for example, Ss in a high base-rate condition were more likely to predict that a given student planned to enroll for further training than were Ss in a low base-rate condition. The base-rate variable had a greater influence than might have been anticipated from the Ss' confidence ratings or from their replies to a series of postexperimental questions concerning the cues they had relied on in formulating their predictions. Nonetheless, the base-rate data were substantially less influential than a Bayesian model would require. In contrast to D. Kahneman and A. Tversky's (1973) analysis, individuating information that reflected a high (vs low) degree of representativeness did not determine the magnitude of the base-rate effect. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

More illusions.

Replies to comments by H. J. Eysenck, S. E. Taylor and J. D. Brown, and T. E. Joiner (see PA, Vols 5447; 5471; and 5454, respectively) on the argument by J. Schedler et al (see record 1994-09623-001) that standard mental health scales may not distinguish genuine from illusory mental health. Methodological issues (e.g., clinical judgment vs self-report measures) are addressed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Winning and positive affect can lead to reckless gambling.

Experiments 1 and 2 examined whether winning versus losing led to reckless betting for real prize money. Experiment 2 also assessed whether positive or negative emotions were linked to such reckless betting. College students were randomly assigned to experience primarily either wins or losses during the rigged first round of a computerized card tournament that had 2 independent rounds. For the second round, participants’ chip totals were reset and cards were dealt randomly. In Experiment 1 (N = 107), participants in the Initial-Winning, as compared with the Initial-Losing, condition bet more recklessly (i.e., bet too many chips when a loss was likely). Experiment 2 (N = 72) again showed that Initial-Winning participants bet significantly more recklessly than did Initial-Losing participants. It also revealed that positive affect was significantly positively correlated with such reckless betting. These findings have implications for understanding how college students, those at an age when they are especially vulnerable to problem gambling, can come to lose more money than they can afford. Initially winning and positive affect when gambling could be risk factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding modality can affect memory accuracy via retrieval orientation.

Research indicates that false memory is lower following visual than auditory study, potentially because visual information is more distinctive. In the present study we tested the extent to which retrieval orientation can cause a modality effect on memory accuracy. Participants studied unrelated words in different modalities, followed by criterial recollection tests that selectively oriented retrieval toward one study modality at a time. Memory errors were lower when oriented toward visual than toward auditory information, thereby generalizing the modality effect to an explicit source memory task. Moreover, these effects persisted independent of the test presentation modality, indicating that retrieval orientation overrode the potential cuing properties of the test stimulus. An independent manipulation check confirmed that visual recollections were subjectively experienced as more distinctive than auditory recollections. These results suggest that retrieval orientation is sufficient to cause a modality effect on memory accuracy by focusing monitoring processes on the recollection of studied features that are diagnostic of prior presentation. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

10 years of illusions.

A decade ago, S. Aglioti, J. F. X. DeSouza, and M. A. Goodale (1995) published an experiment that has had a big influence on the way that visual information is thought to control human behavior. Their findings have often been simplified as suggesting that action is immune to perceptual illusions. The current authors critically analyze the 4 steps involved in this simplification and argue that research during the last 10 years has shown that the validity of 3 of the 4 steps is doubtful. They conclude that this experiment cannot be regarded as firm support for the 2-visual-systems hypothesis (i.e., that the ventral stream is for perception and the dorsal stream is for visually guided actions). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interleukin 8 can affect inner ear function

The chemokine interleukin 8 (IL-8) was instilled into the round window niche of rats through a small perforation in the tympanic membrane in order to study its effect on inner ear function by electrophysiological and morphological techniques. The frequency-specific auditory brainstem response (ABR) was recorded at the frequencies 4, 8, 10, 12, 16 and 20 kHz just before and 1, 2, 5 and 14 days after instilling IL-8 to ascertain the hearing level during each interval. Morphological examination by light microscopy was performed during the same interval following the instillation of IL-8. On day 1, the rise in ABR threshold was within 5 dB SPL (non-significant elevation). However, a significant threshold elevation (above 5 dB SPL) occurred in high-frequency areas (16 and 20 kHz) on day 2, and in middle frequency areas (10 and 12 kHz) on day 5 with sensorineural hearing loss type intensity-latency curves. By day 14, the elevated thresholds had returned to pre-instillation levels. In the lowest areas (4 and 8 kHz), no significant threshold elevation was detected at any time during the observation period. By light microscopy, on day 1, clusters of inflammatory cells (predominantly neutrophils) were observed just outside the round window membrane (RWM), while only a few neutrophils were detected in the cochlea. These cells were still present outside the RWM on day 2. The neutrophils had disappeared by day 5 and only macrophages were present on the middle ear side of the RWM. However, throughout the observation period, the organ of Corti and stria vascularis appeared to be intact. These results suggest that IL-8 in the middle ear cavity is able to influence inner ear function.     

Excess dietary protein can adversely affect bone

The average American diet, which is high in protein and low in fruits and vegetables, generates a large amount of acid, mainly as sulfates and phosphates. The kidneys respond to this dietary acid challenge with net acid excretion, as well as ammonium and titratable acid excretion. Concurrently, the skeleton supplies buffer by active resorption of bone. Indeed, calciuria is directly related to net acid excretion. Different food proteins differ greatly in their potential acid load, and therefore in their acidogenic effect. A diet high in acid-ash proteins causes excessive calcium loss because of its acidogenic content. The addition of exogenous buffers, as chemical salts or as fruits and vegetables, to a high protein diet results in a less acid urine, a reduction in net acid excretion, reduced ammonium and titratable acid excretion, and decreased calciuria. Bone resorption may be halted, and bone accretion may actually occur. Alkali buffers, whether chemical salts or dietary fruits and vegetables high in potassium, reverse acid-induced obligatory urinary calcium loss. We conclude that excessive dietary protein from foods with high potential renal acid load adversely affects bone, unless buffered by the consumption of alkali-rich foods or supplements.     

Coordination in prehension. Information-based coupling of reaching and grasping

Research using the balanced placebo design seeks to differentiate the physiological and psychological effects of drinking alcohol. Questions regarding the validity of the design center about experimenter instructions, particularly in the antiplacebo cell at higher blood alcohol content (BAC) levels. This study tested the plausibility of two misattribution strategies designed to reduce the conflict between experimenter instructions and internal cues of drunkenness. Forty-two participants (BAC = .055) were told that they received no alcohol, with internal cues of drunkenness said to be produced by a (sham) second drug, a (placebo) tachistoscopic display, or no misattribution given. The placebo drug group reported less alcohol intoxication without reporting less physical impairment than the control or tachistoscopic groups. Doubt of instructions was expressed more frequently in the control group than in the placebo drug group. Mean time to first reported doubt of experimenter instructions was longer for the placebo drug group. A manipulation check designed to account for demand effects indicated that instituting the pharmacologic misattribution increased the success of the manipulation over the control group. Providing a credible attribution for internal symptoms of drunkenness makes experimenter's instructions more credible, improving the validity of the antiplacebo cell of the balanced placebo design.     

Aging and fluency-based illusions in recognition memory.

We examined age-related differences in susceptibility to fluency-based memory illusions. The results from 2 experiments, in which 2 different methods were used to enhance the fluency of recognition test items, revealed that older and young adults did not differ significantly in terms of their overall susceptibility to this type of memory illusion. Older and young adults were also similar in that perceptual fluency did not influence recognition memory responses when there was a mismatch in the sensory modality of the study and test phases. Likewise, a more conceptual fluency manipulation influenced recognition memory responses in both older and young adults regardless of the match in modality. Overall, the results indicate that older adults may not be more vulnerable than young adults to fluency-based illusions of recognition memory. Moreover, young and older adults appear to be comparable in their sensitivity to factors that modulate the influence of fluency on recognition decisions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Why visual and vocal interview cues can affect interviewers' judgments and predict job performance.

Using videotaped interviews with 60 managers in utility companies, the authors found that a composite of vocal interview cues (pitch, pitch variability, speech rate, pauses, and amplitude variability) correlated with supervisory ratings of job performance (r?=?.18, p?r?=?.20, p?r?=?.20, p?r?=?.14, p?r?=?.21, p?     

Psychological resources, positive illusions, and health.

Psychological beliefs such as optimism, personal control, and a sense of meaning are known to be protective of mental health. Are they protective of physical health as well? The authors present a program of research that has tested the implications of cognitive adaptation theory and research on positive illusions for the relation of positive beliefs to disease progression among men infected with HIV. The investigations have revealed that even unrealistically optimistic beliefs about the future may be health protective. The ability to find meaning in the experience is also associated with a less rapid course of illness. Taken together, the research suggests that psychological beliefs such as meaning, control, and optimism act as resources, which may not only preserve mental health in the context of traumatic or life-threatening events but be protective of physical health as well. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The tilt-consistency theory of visual illusions.

The authors argue that changes in the perception of vertical and horizontal caused by local visual cues can account for many classical visual illusions. Because the perception of orientation is influenced more by visual cues than gravity-based cues when the observer is tilted (e.g., S. E. Asch and H. A. Witkin, 1948), the authors predicted that the strength of many visual illusions would increase when observers were tilted 30°. The magnitude of Z?llner, Poggendorff, and Ponzo illusions and the tilt-induction effect substantially increased when observers were tilted. In contrast, the Müller-Lyer illusion and a size constancy illusion, which are not related to orientation perception, were not affected by body orientation. Other theoretical approaches do not predict the obtained pattern of results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of visual illusions on grasping.

In 2 experiments, the Müller-Lyer illusion (F. C. Müller-Lyer, 1889; N?=?16) and the parallel-lines illusion (W. Wundt, 1898; N?=?26) clearly affected maximum preshape aperture in grasping (both ps?     

Typography manipulations can affect priming of word stem completion in older and younger adults.

The experiments reported here investigated whether changes of typography affected priming of word stem completion performance in older and younger adults. Across all experiments, the typeface in which a word appeared at presentation either did or did not match that of its 3-letter stem at test. In Exp 1, no significant evidence of a typography effect was found when words were presented with a sentence judgment or letter judgment task. However, subsequent experiments revealed that, in both older and younger adults, only words presented with a syllable judgment task gave rise to the typography effect (Exps 2–4). Specifically, perforance was greater when the presentation and test typeface matched than when they did not. Exp 5, which used stem-cued recall, did not reveal a difference between syllable and letter judgment tasks. These findings highlight the complex nature of word stem completion performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of mindset on positive illusions.

S. E. Taylor and J. D. Brown's (1988) position that mentally healthy people exhibit positive illusions raises a dilemma: How do people function effectively if their perceptions are positively biased? Using P. M. Gollwitzer's deliberative-implemental mindset distinction, we assessed whether people in a deliberative mindset show less evidence of positive illusions than people in an implemental mindset. Participants completed a mindset task and assessments of mood, self-perceptions, and perceived (in)vulnerability to risk. Deliberation led to worsened mood, greater perceived risk, and poorer self-perceptions, relative to implementation; control (no mindset) participants typically scored in between. Study 3 demonstrated that the mindset manipulation corresponds to how people actually make decisions or implement them. Results suggest that people use relatively realistic thinking when setting goals and more positive thinking when implementing them. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reorganization of prehension components following perturbation of object size.

This study provides a kinematic comparison of the response of 12 older persons (ages 60–70) and 12 young persons (ages 20–26 ) to a perturbation of object size during a reach-to-grasp movement. For 80 out of 100 trials, each participant reached to grasp an illuminated cylinder of either small or large diameter (0.7 and 8.0 cm, respectively). For 20 out of 100 trials, a visual perturbation occurred at movement onset. This perturbation consisted of a switch of illumination from 1 to the other cylinder. For the switch from large to small cylinder, participants changed the distal grasp from whole-hand prehension to precision grip. For the opposite switch, participants changed from precision grip to whole-hand prehension. The older participants successfully adapted to these perturbations but showed a more conservative approach. Generally the approach time as the hand neared the object was prolonged, and the coordination between transport and manipulation components was maintained when comparing perturbed with nonperturbed trials. Young participants showed a more flexible pattern with a decrease or loss of temporal coupling between the components.… (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Positive illusions about marriage among married and single individuals.

The common tendency to describe one's marriage in unrealistic terms has been conceptualized as a positive illusion about marriage. Studies of positive illusions have relied on the logical argument that these perceptions are unreasonably positive. This reasoning is insufficient, because previous studies have relied on volunteer samples with high marital satisfaction and long marital duration, both of which could explain rosy evaluations of one's marriage. The current series of studies examined whether positive marital illusions are an artifact of marital satisfaction and duration. Married and single individuals' estimates of their divorce likelihood and other measures of positive marital illusions revealed that illusions about marriage are not dependent on a volunteer bias, marital satisfaction, or duration. The presence of illusions about a future marriage among single individuals suggests that positive marital illusions are a cultural phenomenon. (PsycINFO Database Record (c) 2010 APA, all rights reserved)