Evidence for all-or-none preperceptual processing in perceptual set

“Set” is known to improve the accuracy of report of the stimulus attributes for which Ss are set to respond. The set may produce this effect by acting on either preperceptual or postperceptual processes, or both. To elucidate the manner by which set produces its effect, this paper explores the consequences of two assumptions concerning set (1) On any given trial, a S is either “set” or “not set”: (2) if “set” by the stimulus information. S’s perception of the stimulus actually improves, whereas, if “not set” by the stimulus reformation, the S’s report correctness is improved by an independent interaction of stimulus and set information on a response process. Evidence is provided for both these assumptions. In addition. It is argued that only set given before stimulation can affect a perceptual process.     

Motivation concepts and sexual identity

The association dimension of the Picture Identification Test (PIT) was used to investigate the motivation concepts of male and female university students classified as Declared Homosexual, Sexually Uncertain, Clinical Control, and Normal Control. The t test was used to identify Need Association Dyads which discriminated (p < .01) groups. Greater than chance numbers of variables discriminated each of the pairs of groups within each sex except the Sexually Uncertain versus Clinical Control Male groups, the Declared Homosexual versus Clinical Control Female groups, and the Declared Homosexual versus Normal Control Female groups. PIT Need Association Dyads were discussed as a type of implicit personality theory assessment with emphasis on the beliefs subjects hold about the simultaneous expression of needs.     

Tethered insect flight: A system for automated data processing of behavioral events

Flight mills to which flying insects are tethered, and which allow measurement of locomotion in a circular path, are used to measure flight capability in terms of frequency, duration, velocity, and distance. Also, they are adaptable to measurement of physiological processes such as respiration and energy consumption. We describe a flight-mill system with floating magnets and Teflon® bearings in its rotor that minimize frictional drag. Rotation (of the mill rotor) is transduced by interruption of a light beam to a phototransistor, which produces a signal monitored by a specially constructed event recorder. The event recorder temporarily stores the data from each mill and then transmits them in proper format for permanent storage on seven-track magnetic tape. The system allows simultaneous data collection from 18 individual insects and provides a computerized interpretation of their performance. The result is an analysis of all the significant parameters of flight that can be derived by measuring duration, velocity, distance, and frequency.     

Reduction of intraspecies aggression in rats by positive reinforcement of incompatible behaviors

Fighting responses were elicited by response-independent shocks delivered to pairs of rats. Food pellets were presented following different non-fighting responses to shock: some pairs of rats received pellets dependent upon a specific non-fighting response to shock; others received pellets dependent upon any non-fighting response to shock; and control pairs never received pellets. The mean probability of an elicited aggressive response to shock was reduced to 0.2 by food reinforcement for a specific non-fighting response, and to 0.5 by food reinforcement for any kind of non-fighting response. These values contrasted with the 0.8 probability of elicited aggression when pairs of rats received no food reinforcement. Consistent findings were obtained when treatment conditions were changed for individual pairs of rats.     

The calibration of neutral density wedges

A method for calibrating neutral-density filters is described.     

Instructions,strategies, and pattern uncertainty in a visual discrimination task

A card-sorting task involved discrimination of patterns from the same equivalence set, patterns from different sets of the same size, and patterns from different sets of different sizes. Instructions, experimental conditions, and the number of different patterns to be sorted into two trays were varied in an attempt to change Ss’ strategies from whole-pattern processing to single-element processing. Instructions alone were ineffectual in preventing whole-pattern processing, and physical masks over most of the criterion stimuli (patterns used as guides in sorting) were only somewhat effective. Differences among tasks that were attributable to size of equivalence set were eliminated only by arranging the stimuli so that a whole-pattern strategy required a great deal more information processing, or so that such a strategy could not lead to the required discrimination. The results were interpreted as confirming the influence of the properties of sets of stimuli, as well as the strength of the tendency of human Ss to process and categorize patterns in their entirety. nt]mis|This research was supported in part by a University Research Council grant.     

Postfusional latency in stereoscopic slant perception and the primitives of stereopsis

Random dot stereograms of slanted surfaces were constructed, each representing one or two slanted surfaces in different relative arrangements and with different axes. Latency to fusion and from fusion to stereoscopic resolution was measured for each stimulus. It was found that latency to fusion was always very brief but that latency to stereoscopic resolution varied markedly, depending upon the orientation and arrangement of the stereoscopic surfaces. A gradient of discontinuities at a surface boundary produced an instant slant response for that surface, whereas a gradient of absolute disparities across the surface did not, except under conditions where vertical declination (a form of orientation disparity) was present. We conclude that stereopsis is not based on the primitives used in matching the images for fusion and that it is, at least initially, a response to disparity discontinuities which play no role in the fusion process. We also conclude that vertical declination is responded to globally as a slant around a horizontal axis but that other forms of orientation disparity are ineffective. The evidence from our experiments does not support the existence of a stereoscopic ability to respond globally to differences in magnification (or spatial frequency). It is suggested that stereoscopic perception of slant around a vertical axis is slow because it results from the integration of local processes.