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Results for “Perceptual Distortion”

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PubMed1977

Stability of perceived tension as a function of the menstrual cycle.

The stability of tension judgments among males and females who were either taking or not taking combination low-progestin oral contraceptive pills was investigated. Judgments of interpersonal pressure in videotaped vignettes provided tension measures. The vignettes were presented in two sessions separated by two weeks. Correlations between pressure judgments of .94 for males, .79 for pill females and .40 for non-pill females (all sig less than .002) supported the prediction that non-pill females experience the largest fluctuations in tension across the menstrual cycle. A significant number of non-pill females who changed their scores and who changed from midcycle to premenstrual-menstrual phases or vice versa between the two experimental sessions shifted their tension scores in the predicted direction (p less than .04). As predicted, non-pill females scoring in the lower half on premenstrual-menstrual symptomatology were more consistent in pressure judgments than those high on symptomatology, with correlations of .51 (sig less than .004) and .24 (NS) respectively. Analysis of pressure judgments as a function of menstrual phase and high-low symptomatology indicated a main effect for symptomatology (sig less than .01) with the high group perceiving more pressure. Lack of a main effect for menstrual phase was attributed to large individual variations in tension scores. Results were interpreted as indicating physiological causality underlying the variability in tension across the menstrual cycle. Substituting the Repression-Sensitization dimension for symptomatology yielded no significant results which could lead to a psychological interpretation of such variability.

Contraceptives, Oral, Combined↗
PubMed2002

Attention shifts and memory averaging.

When observers are asked to localize the final position of a moving stimulus, judgements may be influenced by additional elements that are presented in the visual scene. Typically, judgements arc biased toward a salient non-target element. It has been assumed that the non-target element acts as a landmark and attracts the remembered final target position. The present study investigated the effects of briefly flashed non-target elements on localization performance. Similar to landmark attraction, localization was biased toward these elements. However, an influence was only noted if the distractor was presented at the time of target disappearance or briefly thereafter. It is suggested that memory traces of distracting elements are only averaged with the final target position if they are highly activated at the time the target vanishes.

Adult↗
PubMed1999

Categorisation of action speed and estimated event duration.

Two experiments investigated the relationship between the words used to describe event actions and estimates of event duration, and whether this relationship might account for some of the variation found in duration estimates. Experiment 1 manipulated sets of action words within an account of a robbery, and replicated the Burt and Popple (1996, Experiment 1) finding that estimated duration decreased as the implied action speed of the robbery increased. Experiment 2 found considerable variation across individuals in the action words they used to describe a robbery, and that the number of action words used was negatively correlated with estimated duration. Taken together the experiments suggest that the interaction between individual differences in action categorisation and the use of inferences about the relationship between action speed and event duration, may account for some of the between-subject variation found in estimates of event duration.

Adolescent↗
PubMedDate not supplied

Actual vs perceived EMS response time.

OBJECTIVE: To compare patients' perceptions of ambulance response times with the actual ambulance response times to aid quality assurance efforts in EMS management. METHODS: A convenience sample of patients presenting to an urban ED via EMS were asked a series of four questions pertaining to response time, scene time, time to definitive care, and their expectations of response time. These times were then compared with actual times from the EMS dispatch center. Times were analyzed using multivariate analysis of variance (MANOVA) followed by discriminant analysis. RESULTS: There was a significant difference between the perceived and actual times for all three questions, by both multivariate analysis and univariate analysis (p < 0.0001). Patients tended to overestimate the actual response times (12.4 min vs 9.1 min) but underestimate the on-scene times (9.1 min vs 12.4 min) and times to definitive care (29.4 min vs 35.0 min). CONCLUSION: Patients are inaccurate in their estimations of time. Response times are generally overestimated, while scene times and times to definitive care are underestimated. Actual response times often meet patients' expectations (mean 10.8 min), although the patients may not perceive that they have.

Attitude↗
PubMed2005

Abnormal visual search in mild cognitive impairment and Alzheimer's disease.

Our aim was to further characterize the clinical concept of mild cognitive impairment (MCI). We examined the status of visual attention-related processing in such patients in relation to healthy older adults and patients with Alzheimer's disease (AD) by measuring performance on a computer-based visual search task. We tested 20 older adult control participants, 13 patients with amnestic mild cognitive impairment and 12 patients with AD. Patients with AD and with MCI exhibited a significant detriment in visual search performance compared to the older adult controls. The deficit in visual search was greater for the patients with AD than the patients with MCI. The pattern of results displayed by the MCI group indicates that patients who appear clinically to suffer only from a deficit in memory also display a deficit in visual attention-related processing, which although not as severe as those with AD, represents a significant detriment in such performance compared to that seen in healthy ageing.

Aged↗
PubMed2006

Abnormal configural face perception in a patient with right anterior temporal lobe atrophy.

Face perception is a vital aspect of human social functioning and involves specialized cognitive and neural mechanisms. For example, configural face processing involves determining the relationship between the parts of the face, and this process enables us to differentiate between different faces. Here, we report an unusual case in which right anterior temporal lobe atrophy resulted in a profound deficit in the ability to recognize faces. We demonstrate that this patient is not able to process faces via configural information, raising the possibility that the right anterior temporal lobe has a role in configural face processing.

Atrophy↗
PubMed2004

The role of the cerebral hemispheres in specific versus abstract priming.

The present study examined specific and abstract priming for pictures in unilateral brain-damaged patients using a picture fragment identification task. Participants were 10 posterior right hemisphere (RH) damaged patients, 11 posterior left hemisphere (LH) damaged patients, and 30 healthy normal controls. Results reveal that RH patients perform specific priming tasks significantly worse than healthy participants (p < .005). There was a trend (p < .1) towards worse abstract priming in LH patients when compared to healthy participants. These results are additional evidence that specific priming depends on normal functioning of the posterior right cerebral hemisphere, while abstract priming depends on normal functioning of the posterior left cerebral hemisphere, and extend this finding from verbal to non-verbal stimuli.

Aged↗
PubMed2000

Why are familiar-only experiences more frequent for voices than for faces?

Hanley, Smith, and Hadfield (1998) showed that when participants were asked to recognize famous people from hearing their voice, there was a relatively large number of trials in which the celebrity's voice was felt to be familiar but biographical information about the person could not be retrieved. When a face was found familiar, however, the celebrity's occupation was significantly more likely to be recalled. This finding is consistent with the view that it is much more difficult to associate biographical information with voices than with faces. Nevertheless, recognition level was much lower for voices than for faces in Hanley et al.'s study, and participants made significantly more false alarms in the voice condition. In the present study, recognition performance in the face condition was brought down to the same level as recognition in the voice condition by presenting the faces out of focus. Under these circumstances, it proved just as difficult to recall the occupations of faces found familiar as it was to recall the occupations of voices found familiar. In other words, there was an equally large number of familiar-only responses when faces were presented out of focus as in the voice condition. It is argued that these results provide no support for the view that it is relatively difficult to associate biographical information with a person's voice. It is suggested instead that associative connections between processing units at different levels in the voice-processing system are much weaker than is the case with the corresponding units in the face-processing system. This will reduce the recall of occupations from voices even when the voice has been found familiar. A simulation was performed using the latest version of the IAC model of person recognition (Burton, Bruce, & Hancock, 1999) which demonstrated that the model can readily accommodate the pattern of results obtained in this study.

Adolescent↗