Sensory interactions in bilateral kinesthesia

Three experiments are reported that examine the masking effect on the detection of kinesthetic targets from noise presented simultaneously on the same hand or on a different hand as the target. Performance was facilitated when noise on the two hands was correlated versus uncorrelated or when it occurred on just one hand. The data are consistent with correlated input on the two hands being compared and used to reduce noise effects. Moreover, participants ignored uncorrelated noise from nontarget hands when they knew in which hand the targets would occur. There was no effect of shifts from uncorrelated to correlated noise 200 msec prior to targets, suggesting that such bottom-up changes were insufficient to induce comparison across the hands. In contrast, shifts from correlated to uncorrelated noise 200 msec prior to the target had performance at the same level as that with uncorrelated noise throughout the trial. This result indicates that the loss of correlation was detected within this interval and thatwhen the target's location was known, participants were then able to switch attention to the target hand. The interactions between attentional filtering and the correlation on the processing of bilateral kinesthetic inputs are discussed.     

The role of motor simulation in action perception: a neuropsychological case study

Research on embodied cognition stresses that bodily and motor processes constrain how we perceive others. Regarding action perception the most prominent hypothesis is that observed actions are matched to the observer’s own motor representations. Previous findings demonstrate that the motor laws that constrain one’s performance also constrain one’s perception of others’ actions. The present neuropsychological case study asked whether neurological impairments affect a person’s performance and action perception in the same way. The results showed that patient DS, who suffers from a frontal brain lesion, not only ignored target size when performing movements but also when asked to judge whether others can perform the same movements. In other words DS showed the same violation of Fitts’s law when performing and observing actions. These results further support the assumption of close perception action links and the assumption that these links recruit predictive mechanisms residing in the motor system.     

Categorizing chairs and naming pears: Category differences in object processing as a function of task and priming

Four experiments are reported examining the locus of structural similarity effects in picture recognition and naming with normal subjects. Subjects carried out superordinate categorization and naming tasks with picture and word forms of clothing, furniture, fruit, and vegetable exemplars. The main findings were as follows: (1) Responses to pictures of fruit and vegetables (\ldstructurally similar\rd objects) were slowed relative to pictures of clothing and furniture (\ldstructurally dissimilar\rd objects). This structural similarity difference was greater for picture naming than for superordinate categorization of pictures. (2) Structural similarity effects in picture naming were reduced by repetition priming. Repetition priming effects were equivalent from picture and word naming as prime tasks. (3) However, superordinate categorization of the prime did not produce the structural similarity effects on priming found for picture naming. Furthermore, such priming effects did not arise for picture or word categorization or for reading picture names as target tasks. It is proposed that structural similarity effects on priming object processing are located in processes mapping semantic representations of pictures to name representations required to select names for objects. Visually based competition between fruit and vegetables produces competition in name selection, which is reduced by priming the mappings between semantic and name representations.     

Contiguity and contingency in instrumental conditioning

There have been several attempts to construct molar theories of conditioning on the empirical basis that response-reinforcement contingency is important in determining conditioning. Such theories claim to explain behavior in terms of molar level processes which transcend the molecular level and, therefore, are not reducible to molecular processes or their interaction. These molar theories are critically examined and found to be seriously flawed because they fail to account for the effects of delaying reinforcement (degree of contiguity). Observed molar level relations, such as the matching law, do not require a molar theory, but may be more usefully considered as a product of molecular processes.     

Book reviews

Sutherland, S. (1989). Macmillan dictionary of psychology. London: Macmillan Reference Books. ISBN -333-38829-1. £ 29.95

Van Toller, S. & Dodd, G. H. (Eds.). (1988). Perfumery: the psychology and biology of fragrance. London: Chapman and Hall. Pp. 268. ISBN 0-412-30010-9. £ 35.00

Watt, R. J. (1987). Visual processing: Computational, psychophysical and cognitive resedrch. Hove: Lawrence Erlbaum Associates Ltd. Pp.160. ISBN 0-86377-081-9. £ 14.95/$ 26.95

Caplan, D. & Hildebrandt, N. (1988). disorders of syntactic comprehension. Cambridge, MA: MIT Press/Bradford Books. Pp. 340. ISBN 0-262-03132-9. £31.50     

Spreading suppression and the guidance of search by movement: Evidence from negative color carry-over effects

A growing number of studies have shown that significant impairments to search and selection can occur if the target item carries a feature of the irrelevant distractors currently being ignored Braithwaite, Humphreys, and Hodsoll (Journal of Experimental Psychology: Human Perception and Performance, 29, 758–778, 2003). However, these effects have been documented only when search has been extended over time (i.e., in preview search), and not in standard search displays with simultaneously presented items. Here, we present the first evidence that similar costs to selection can occur in simultaneous displays under appropriate circumstances. In the present experiment, participants searched a display for a moving target letter among static and moving distractors. Search efficiency was significantly enhanced for a moving target when half of the letters moved (and half remained static), allowing the static items to be excluded from search. However, if the moving target then shared its color with the irrelevant static items, significant costs emerged, relative to baselines. These results are consistent with the involvement of a general feature-based suppression mechanism in selection, operating over space as well as time.     

Two components in IOR: evidence for response bias and perceptual processing delays using the SAT methodology

Inhibition of return (IOR) occurs when reaction times (RTs) are slowed to respond to a target that appears at a previously attended location. We used the speed-accuracy trade-off (SAT) procedure to obtain conjoint measures of IOR on sensitivity and processing speed by presenting targets at cued and uncued locations. The results showed that IOR is associated with both delays in processing speed and shifts in response criterion. When the target was briefly presented, the results supported a criterion shift account of IOR. However, when the target was presented until response, the evidence indicated that, in addition to a response bias effect, there was an increase in the minimal time required for information about the target to accumulate above chance level. A hybrid account of IOR is suggested that describes effects on both response bias and perceptual processing.     

Contiguity, reinforcement rate and the law of effect

There is an ambiguity in formulations of the Law of Effect which stress the importance of the correlation of rate of responding with frequency of reinforcement. The main problem is that such theories have not specified precisely how the correlation of response and reinforcement rates should be determined, with the result that the theories can become irrefutable. Two experiments were carried out which expose some of the problems created by this ambiguity. “Free” food reinforcers were delivered to rats in the absence of responding. Lever responses intermittently provided immediate (contiguous) reinforcement, but cancelled some of the following “free” reinforcements. Responding was established and maintained even when the overall rate of responding was negatively correlated with the overall frequency of reinforcement. Several ways in which correlational theories could attempt to accommodate these results are discussed but rejected as unsatisfactory, either because they severely limit the scope of the theories or because they lose their most important feature: that of treating behaviour at a molar rather than a molecular level.     

Action relations, semantic relations, and familiarity of spatial position in Balint’s syndrome: Crossover effects on perceptual report and on localization

We contrasted effects of the action relationship between objects, relative to effects of semantic relation and familiarity of spatial location, in a patient with Balint’s syndrome. We found enhanced perceptual report of objects placed in the correct colocations for action in comparison with when the objects (1) were placed in incorrect locations for action (Experiment 1), (2) were associatively related (Experiment 2), or (3) fell in familiar locations but were not action related (Experiment 4). In contrast, the ability to localize the objects was affected by whether the objects were in familiar as opposed to unfamiliar locations with respect to one another. Action relations between objects facilitate joint attention to both objects but do not facilitate binding to location. Familiar spatial relations facilitate spatial binding, but do not cue joint attention to the stimuli. Effects of action relation on attention and localization can be dissociated from effects of semantic relationship and familiarity of spatial location on attention and localization.     

Revisiting preview search at isoluminance: new onsets are not necessary for the preview advantage

It has been argued that search performance under preview conditions relies on automatic capture by luminance onsets (Donk & Theeuwes, 2001). We present three experiments in which preview search was examined with both isoluminant and nonisoluminant items (e.g., as defined by luminance onsets). Experiment 1 provided evidence against the automatic capture of attention by onsets. Search benefited when onset previews were followed by new onset stimuli, as compared with a full-set baseline matched for the number of new onsets but in which half the distractors appeared simultaneously at isoluminance. Furthermore, both Experiments 1 and 2 established a preview advantage when isoluminant targets followed onset previews, when compared with appropriate full-set baselines. Experiment 3 replicated this result, while showing that the preview benefit was disrupted by dual-task interference. The data indicate that new onsets are not necessary to generate a preview advantage in search. We discuss the data in terms of search's benefiting from active inhibition of old onset-defined stimuli.