Visual distortion of body size modulates pain perception

Pain is a complex subjective experience that is shaped by numerous contextual factors. For example, simply viewing the body reduces the reported intensity of acute physical pain. In this study, we investigated whether this visually induced analgesia is modulated by the visual size of the stimulated body part. We measured contact heat-pain thresholds while participants viewed either their own hand or a neutral object in three size conditions: reduced, actual size, or enlarged. Vision of the body was analgesic, increasing heat-pain thresholds by an average of 3.2 °C. We further found that visual enlargement of the viewed hand enhanced analgesia, whereas visual reduction of the hand decreased analgesia. These results demonstrate that pain perception depends on multisensory representations of the body and that visual distortions of body size modulate sensory components of pain.     

Recognition memory for faces with and without spectacles

23 students were tested for memory on 40 faces, half of which were bespectacled. 20 photographs were shown for 1 sec., then mixed with the 20 others for testing. Recognition was poorer for faces with than without glasses, and women generally performed relatively better on females' faces.     

Visual search with imperfect recognition

A task involving both the search for and recognition of one of two possible critical elements embedded in a set of noise elements was investigated with the aid of a mathematical model. The model consists of three processes, these being search, recognition, and decision. The first of two experiments attempted to show the operation of two separate bias parameters in the decision process. While the results were in the right direction, the data did not unequivocally establish the necessity of two bias parameters. In the second study, it was found that while a S’s ability to find a critical element in a display decreased as the number of noise elements in the display increased, his ability to recognize which critical element it was after finding it remained constant. This result was interpreted as supporting a strictly all-or-none view of the search process.     

The role of spectacles in facial memory: a replication and extension

A total of 187 subjects in three conditions involving 1- or 3-sec. exposure times and 10-min. or 7-day delays were shown 20 photographs of faces, half of which were bespectacled, and then tested from a set of 40 consisting of the original 20 mixed up with 20 new ones, half of which were also bespectacled. Accuracy of recognition declined with shorter exposure and longer delay and was lower for faces with than without spectacles at the shorter delay. In all three conditions, there were more false-alarms for faces with than without glasses. It is concluded that eyeglasses did not serve as an efficient discriminating feature in recognition memory, and it is recommended that positive eyewitness identification of people wearing spectacles be treated with particular caution.     

Self-notions and top-down distortion

Abstract

John Perry offers an unusually substantive, and initially plausible, account of the conceptual role of first-person thought. This paper critiques Perry’s account, particularly in what it says about action explanation, and offers a partial alternative. It also identifies three high-level assumptions about what accounts of conceptual roles should look like that plausibly explain why Perry’s account goes off track in the ways that it does – this is the top-down distortion of the title. Identifying and arguing against the three assumptions helps point in the direction of a better account.     

Visual search asymmetry with uncertain targets

The underlying mechanism of search asymmetry is still unknown. Many computational models postulate top-down selection of target-defining features as a crucial factor. This feature selection account implies, and other theories implicitly assume, that predefined target identity is necessary for search asymmetry. The authors tested the validity of the feature selection account using a singleton search task without a predefined target. Participants conducted a target-defined and a singleton search task with a circle (O) and a circle with a vertical bar (Q). Search asymmetry was observed in both tasks with almost identical magnitude. The results were not due to trial-by-trial feature selection, because search asymmetry persisted even when the target was completely unpredictable. Asymmetry in the singleton search was also observed with more complex stimuli, Kanji characters. These results suggest that feature selection is not necessary for search asymmetry, and they impose important constraints on current visual search theories.     

Visual selective attention with virtual barriers

Previous studies have shown that interference effects in the flanker task are reduced when physical barriers (e.g., hands) are placed around rather than below a target flanked by distractors. One explanation of this finding is the referential coding hypothesis, whereby the barriers serve as reference objects for allocating attention. In five experiments, the generality of the referential coding hypothesis was tested by investigating whether interference effects are modulated by the placement of virtual barriers (e.g., parentheses). Modulation of flanker interference was found only when target and distractors differed in size and the virtual barriers were beveled wood-grain objects. Under these conditions and those of previous studies, the author conjectures that an impression of depth was produced when the barriers were around the target, such that the target was perceived to be on a different depth plane than the distractors. Perception of depth in the stimulus display might have led to referential coding of the stimuli in three-dimensional (3-D) space, influencing the allocation of attention beyond the horizontal and vertical dimensions. This 3-D referential coding hypothesis is consistent with research on selective attention in 3-D space that shows flanker interference is reduced when target and distractors are separated in depth.     

Prism distortion and accommodative change

The literature concerning oculomotor changes during adaptation to prism distortion has dealt mainly with the question of eye movements. The present study examined accommodation during exposure to distortion by ophthalmic prisms. Ss were asked to fixate four targets of equal visual angle at four distances. Accommodation was measured at each distance by means of a Laser-Badal optometer. Repeated measures for the same target distances were obtained prior to during and after exposure to binocular prisms. The results indicated that prisms induce underaccommodation at each of the target distances, although the total range of predistortion and distortion accommodation was restricted. Significant recovery from the effects of induced underaccommodation was observed at near target distances. No significant aftereffects of wearing the prisms was observed. In a second experiment, where target background contrast was increased, consistent underaccommodation was again observed and recover was observed at the near target distance. The range of accommodative change was also considerably improved. It was concluded that the angular magnification of ophthalmic prisms induced underaccommodation. It was suggested that partial recovery from the prism effect may be related to alterations in vergence.     

Reinforcing capabilities of television distortion

The effectiveness of television distortion as a negative reinforcer was analyzed. Contingency arrangements involving television distortion were found to be capable of (a) accelerating the work rate of a naive, mildly retarded subject on a simulated production-line task involving card-sorting, and (b) reducing gross hyperactivity of a mildly retarded subject. An escape-avoidance contingency was arranged for the production-line behavior of the first subject and a punishment contingency for the hyperactive behavior of the second subject. Television distortion appears to be an effective and practical negative reinforcer for use in behavior modification.     

Memory distortion in group recall

Earlier we reported (Basden, Basden, Bryner, ...Thomas, 1997) that, in comparison with nominal groups (three people tested individually), three-person collaborative groups recalled fewer presented words but intruded more nonpresented words. In the present research, Experiment 1 showed that when presented words were associatively related to critical nonpresented words, collaboration inhibited recall of presented words but did not influence recall of critical nonpresented words. Experiment 2 showed that with categorized lists, recall of high taxonomic frequency critical nonpresented words was greater for collaborative groups than for nominal groups. Collaboration did not inhibit recall of presented words, presumably because guessing supplemented recall in collaborative groups. Greater false recall in collaborative than in nominal groups appears to result from activation of superordinate-to-item associations rather than item-to-item associations.