Binocular Rivalry Disrupts Visual Priming

Many results implicate perceptual processing in repetition priming, but little is known of potential mechanisms for priming. A new method was used to help determine the processing stage at which priming occurs. Priming pictures were presented under dominance or suppression generated by binocular rivalry. Although low-level, sensory attributes can be processed under rivalry suppression, there is no evidence that repetition priming can be supported by such low-level processing. Priming was found only for stimuli that were processed sufficiently to be identified in the priming stage. The results demonstrate that repetition priming requires processing of stimulus attributes into relatively high-level representations.     

Upper and lower visual field differences in categorical and coordinate judgments

Kosslyn (1987) theorized that the left and right hemispheres differ in processing categorical and coordinate spatial relationships, respectively. Previc (1990) hypothesized that the upper and lower visual fields are functionally specialized for visual search and visuomotor manipulations, respectively. Conceptual similarities between these two theories suggested possible upper visual field advantages for categorical judgments and lower visual field advantages for coordinate judgments. In the present two experiments, subjects made either categorical or coordinate judgments to stimuli in the upper left, upper right, lower left, or lower right visual fields. The first experiment manipulated categorical/coordinate judgments as a between-subjects variable. The second experiment manipulated categorical/coordinate judgments as a within-subjects variable. In the first experiment, reaction times (RTs) for categorical judgments were equal in all visual fields except the lower left, in which RTs were slower. For coordinate judgments, RTs were equal in all visual fields except the lower left, in which RTs were faster. In general, these effects were replicated in the second experiment. However, there appeared to be consequences associated with manipulating the categorical/coordinate variable in a within-subjects fashion. The requirements of visual search versus visuomotor processes appear to map onto the nature of categorical versus coordinate processing, respectively, suggesting possible upper-lower visual field differences in categorical versus coordinate processing.     

Content: Covariation,control and contingency

The Representational Theory of the Mind allows for psychological explanations couched in terms of the contents of propositional attitudes. Propositional attitudes themselves are taken to be relations to mental representations. These representations (partially) determine the contents of the attitudes in which they figure. Thus, Representationalism owes an explanation of the contents of mental representations. This essay constitutes an atomistic theory of the content of formally or syntactically simple mental representation, proposing that the content of such a representation is determined by the intersection of the representation's correlational and control properties. The theory is distinguished from standard information-based accounts of mental content in allowing that the relevant correlations be contingent while insisting on an efferent aspect to mental content. The theory on offer allows for a natural explanation of misrepresentation, finds a niche for the notion ofnarrow content, welcomes radical first person fallibility with respect to questions of content, admits of mental ambiguity and recognizes that the future of a psychological agent is a factor in determining the content of the agent's present psychological states.     

Improving the encoding of verbal reports by using MPAS: A computer-aided encoding system

The dramatically increased use of verbal report methodologies in psychological research has created a need for new tools to improve the efficiency and reliability of encoding these data. A computer-aided protocol encoding system called MPAS (Multiple Protocol Analysis System) presents individual protocol segments in a randomised order to one or more coders and then stores computer keyboard-entered codes for later output to an SPSS formatted data file. In the present paper, MPAS is described, and a brief example is provided of how MPAS can be used in a con-trolled laboratory study to rigorously analyze verbal protocol data.     

Occupational stress and burnout amongst staff working with people with an intellectual disability

The Occupational Stress Inventory (Osipow & Spokane, 1987) and the Maslach Burnout Inventory (Maslach, 1982) were used to assess the levels of occupational stress and burnout amongst staff providing services to people with an intellectual disability both in an institutional and community settings. Data were analyzed to determine the effects of direct client contact, staff mental health, and working environment (institution vs. community). While levels of burnout and occupational stress were not high overall, staff working in an institutional setting scores more highly.     

Feature selection and classification: A developmental study

Two hundred and thirteen children between the ages of 4 and 16 sorted 30 complex objects freely into groups. These were either schematic faces, schematic imaginary animals, or histoform patterns and were constructed from 9 independently and continuously varying features, each with 10 levels. The three sets were equivalent in terms of underlying numerical structure. A new method of analysis of the groups formed yielded the following direct measures of subjective organization in the sorting of each child: the number of features used in sorting, the accuracy of sorting, and the number of independent dimensions of classification. Both the material and the analysis of sorting were devised on the assumption that only some of the component features of complex objects are used for classification, while others are ignored. Sorting performance differed markedly both with age and with different types of material. The improvement in sorting ability with age, except for the youngest children, could be attributed to an increase in the number of features used rather than an improvement in the accuracy of use. In contrast, the poor sorting of histoform patterns as opposed to faces and animals was due to a low level of sorting accuracy. The basic results on the development of classification confirmed previous studies, and hence suggest that it is valid to consider feature selection as a basic component of classification.     

Recovery of the US representation over time during extinction

Four experiments used a conditioned suppression procedure in rats to explore changes in the US representation over time during the course of extinction. They employed two previously reported effects: reinstatement of responding to an extinguished CS by separate US presentation, and the erasure of that effect by interposed nonreinforcement of a second excitatory CS. These effects have been interpreted as enhancing and depressing the US representation, respectively. Experiment 1 found the erasing effect to decrease but still to remain substantial after over a 4-day period, suggesting a partial recovery with time of a deliberately depressed US representation. Experiment 2 implicated this change as a contributor to the phenomenon of spontaneous recovery by showing that recovery to be sensitive to erasure effects. Experiments 3 and 4 found evidence for an interaction between the state of the US representation and the amount of associative change which results from nonreinforcement of an excitatory CS. When the US representation was strong, either because of reinstatement or the passage of time, nonreinforcement of a CS was especially effective in producing associative change. When the US representation had been depressed by erasure, those nonreinforcements produced relatively less associative loss. Moreover, these effects upon associations were reasonably stable in the sense that they left asymptotic differences in the strength of associations after extinction. Together with previous findings, these results point to an important role for the US representation in the performance and learning which occurs during extinction.     

The visual system of the cat

So much of our current knowledge about the neurophysiology of vision has come from studying the visual system of the cat. Using microelectrode techniques, neurophysiologists have examined in great detail the spatial properties of receptive fields of neurons at various levels of the feline nervous system, and headway is now being made in discovering the patterns of neural connections which give rise to the remarkable degree of stimulus selectivity characteristic of these neurons. This paper reviews the major findings concerning the visual system of the normal adult cat, from optics to visual cortex, and summarizes the physiological consequences of early visual deprivation on the visual nervous system of the cat. The review concludes with remarks about the validity of generalizing from cat neurophysiology to human vision.