Vibrotactile vigilance: The effects of costs and values on signals

Vibrotactile vigilance behavior was examined for the effects on signal detection performance of placing costs on misses and false detections and a positive value on the correct detection of a signal. Analyses over time showing that the frequencies of correct detection and false detection of signals decreased, while response times increased, indicated that increased costs for misses and false alarms lead to poorer correct detection performance, while the value placed on the correct detection of a signal had little effect. The d’ statistic of signal detection theory was invariant with both signal costs and time, while β varied with both factors.These results imply that the performance decrement during a vigil was due to an increased strictness in the criterion (β) the S set for deciding whether or not a signal was present. The cost factors were effective in manipulating performance during the watch by causing changes in the S’s decision criteria. Findings from this study clearly support those predicted by the “Decision Theory” of Swets, Tanner, and Birdsall (1961); this is suggested as perhaps being the best available basis for a theory of vigilance at this time.     

The relationship between cognitive,motor-kinesthetic,and oculomotor adaptation

The literature concerning adaptation to prism indicates that several adaptive mechanisms may be important. The particular mechanism or mechanisms involved depends (at least in part) upon the type of adaptive exposure. In the present study. three adaptive mechanisms (cognitive. oculomotor, and motor-kinesthetic) were investigated. Ss were asked to point in the dark at an illuminated target. The target was seen displaced from its veridical position due to a wedge prism placed before S’s right eye. The left eye was occluded. Ss then viewed their visual target pointing errors through the displacing prism without seeing any part of their bodies. One group of Ss was instructed to ignore these prism-induced errors and to continue pointing at the target’s visual position. A second group of Ss was instructed to compensate fully for their errors and to at tempt to eliminate them on all future trials. For the latter group errors were completely eliminated, while for Ss instructed to ignore their errors, relatively small improvement in visual target settings occurred. This improvement was called cognitive adaptation, since it depended on the S’s conscious control. In addition. for both conditions. evidence was found that allowing Ss to view their prism-induced pointing errors resulted in some form of motor-kinesthetic adaptation. This adaptation was hypothesized to represent a change in the judged position of the pointing hand relative to its felt position. It was concluded that this motor-kinesthetic adaptation was dependent, in part, upon cognitive information concerning the effects of the prism and that it serves to reduce conflict between cognitive and visual cues, i.e., between what S believes and what he sees.     

Visual capture of haptically judged depth

Using a graduated scale. S was required to match with his left hand the depth of three objects of equal physical depth (or thickness) held with the right hand. While making these haptic depth judgments the objects were viewed. Due to its optical properties. one object was of greater apparent visual depth than the other two, which served as controls. The critical object was judged to be of greater haptic depth than the control objects, thus demonstrating visual capture of haptic depth. This outcome is similar to that noted previously for haptically judged direction, size, and orientation with transformed visual input.     

Über Wahrnehmungsverhalten beim 8- bis 10wöchigen Säugling

Zusammenfassung Im Rahmen einer Systemtheorie des Verhaltens und der Persönlichkeit und auf dem Hintergrund der Ergebnisse der Berner Längsschnittuntersuchungen wird eine Hypothese über die Genese der Wahrnehmung entwickelt, wonach die frühesten Wahrnehmungen im wesentlichen Verarbeitungen der Reizwirkungen in einer von zwei Klassen von Verhaltenssystemen sind, nämlich der Abwendung und Selbstsicherung (A-Systeme) bzw. der Zuwendung zur Außenwelt (Z-Systeme).In einem Experiment mit 8-, 9- und l0wöchigen Säuglingen wurde das Wahrnehmungsverhalten in Abhängigkeit von verschiedenen Reizfiguren, von der individuellen Eigenart und vom Aktivationsniveau des Kindes mit Hilfe eines Zeitstichprobenverfahrens beobachtet. Der auf die Differenzierung zwischen den verschiedenen Reizfiguren entfallende Varianzanteil steigt mit zunehmendem Alter an, während die Wirkung der autonomen Aktivationsprozesse allmählich zurücktritt. Mit 10 Wochen kann eine geordnete Form oder gute Gestalt leichter verarbeitet werden als eine mehr zufällige Form.Einige Probleme im Zusammenhang mit Annahmen, Methoden und Ergebnissen des Experiments werden diskutiert, darunter die Theorie der Formwahrnehmung, die Genese von Subjekt- und Objektsystem und die beschränkte Bedeutung der Methode der bevorzugten Fixierung in der Erforschung der Säuglingswahrnehmung.

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Summary Within the framework of a System Theory of behavior and personality and against the background of the results of the Bernese Longitudinal Studies, a hypothesis of the genesis of perception is developed. It states that the earliest perceptions are essentially integrations of the effects of stimuli into one of two classes of behavioral systems, viz. withdrawal and self-preservation (A-systems) or, respectively, approach to the outer world (Z-systems).The perceptual behavior of 8-, 9-, and 10-week-old infants as a function of different stimulus forms, individuality, and activation level was observed by means of a time-sampling rating method. The proportion of variance accounted for by the differences between stimuli was found to increase with age; at the same time the effect of autonomic activation processes was decreasing. At the age of 10 weeks the infant can work up an orderly form or good Gestalt more readily than a more irregularly-shaped form.Some problems in connection with the assumptions, methods, and results of the study are then discussed, including form perception theory, the genesis of subject- and object-system, and some restriction of the method of preferred fixation in the study of infant perception.

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Gegenwärtig als Canada Council Postdoctoral Fellow an der York University in Toronto, Ont., Canada. Der Verfasser möchte seinem verehrten Lehrer Richard Meili seinen herzlichen Dank für die Anregung dieser Arbeit ausdrücken.     

Intake and Walk-in Procedures in a College Counseling Setting

Modifications of the intake procedure usually employed in counseling settings were adopted in order to provide students the opportunity for immediate contact with a counselor. Elimination of the waiting list, reduction in number of missed appointments, and reduction of length of counseling came about. Staff satisfaction with the new approach has been high and there would be opposition to reverting to the scheduled initial interview. Possible changes in the type of problem or clients' readiness for problem-solving were observed.     

Two types of phenomenal instructions for size and distance judgments of objects presented on a two-dimensional plane

Demand characteristics were studied in a simple situation in which observers made size and distance estimates of stimuli presented on a two-dimensional linear perspective drawing. Half the Ss were asked questions stressing phenomenal report: The other half were asked the same questions preceded by instructions stressing the objective nature of the stimulus configuration but requesting, nonetheless, phenomenal report. Instructions resulted in a significantly greater perspective size illusion but did not affect the distance estimates. No meaningful correlations between size and distance estimates were found.     

Relational perception and modes of perceiver operation

Judgments were made of the size of a small, luminous (inner) square appearing in the center of a somewhat larger, variable (outer) square, the whole pattern appearing in the dark. Accuracy of judgment was greatest when the outer square was constant from trial to trial but deteriorated when the outer square also varied in size, reaching a lower limit less than the accuracy produced under the absolute judgment condition (no outer square presented). An application of multiple discriminant analysis and the use of a maximum likelihood observer model provided estimates of the extent to which Os responded to inner and outer size variation as separate aspects of stimulation. Although Os differed markedly in this respect, their ability to identify inner square size under the various conditions did not reflect this difference.