Selective attention and changes in clinical state

Thirty inpatients of a psychiatric unit were given the Mini-Mult and a series of auditory selective attention tasks in order to test the hypotheses that (1) impaired attention is related to degree of pathology, and (2) improvement in clinical state leads to improved ability to selectively attend. The results showed that the relationship between the Mini-Mult and the listening tasks is significant only when the subjects had to exclude irrelevant stimuli (interference condition). The results also indicated that the relationship between clinical changes and changes in attentional performance is significant. The findings were discussed in terms of a quantitative theory of attention.     

Preparing Individuals for job Interviews: Suggestions From More Than 60 Years of Research

After a review of the existing literature on employment interviews, the findings are organized into a four-phase model for implementing training programs that prepare clients to interview more effectively. The four phases include developing realistic expectations, developing successful interviewing skills, using effective training procedures, and preparing clients to cope with rejection shock. The importance of active preparation for job interviews and the counselor's potential role in this process are emphasized.     

In defence of a ratio model for movement detection at threshold

Sutherland (1961) proposed that the detection of motion might depend upon the ratios of firings in cells sensitive to movement in opposite directions. Sekuler and his collaborators have argued that the notion of a ratio mechanism at threshold is wrong. The findings and arguments upon which this conclusion was based are challenged, an explicit model is described which provides an account of data previously held to be inconsistent with a ratio model, and an experiment is reported which provides unequivocal support for the ratio model and whose findings are inconsistent with the predictions from Sekuler's “independence” model.     

The changing pattern of perceptual analytic strategies and response selection with practice in a two-choice reaction time task

In the experiment reported here the primary hypothesis proposed, which was supported by the data, was that subjects performing a two-choice self-paced serial RT task would learn to change their strategy of perceptual analysis of signals presented to them as they became progressively more practised. Early in practice each signal is identified as a particular state of the display and an appropriate response is then made. Well practised subjects, however, select their responses by reference to the change or constancy between successive displays. This strategy implies that the assumptions made by the generally accepted simple S-R connectionist model of two-choice serial RT may be quite misleading, since the choice of any particular response must be determined not only by the display state but also by what the previous response had been.     

Isolating the typicality effect in semantic memory

An experiment was conducted to isolate the typicality effect in the overall categorization process. Subjects were required to indicate whether or not a probe word was a member of one of a variable number of categories held in memory. The typicality of the probe word, with respect to its superordinate category, was varied as was the physical quality of the probe. These manipulations were designed to test predictions drawn from Collins and Loftus (1975) and Anderson and Reder (1974), as well as a prediction based on the well-known effect of semantic context on word perception. A fourth prediction was drawn from a proposed model which postulates successive access of categories and locates the typicality effect in a within-category search stage. Typicality proved to be additive with stimulus quality and set size, but interacted with response type. These results were interpreted as support for the successive-access within-category search model while disconfirming the alternative predictions.     

On the time constants of tachistoscopes

The time constants of commercially available, electronic tachistoscopes are shown to be much poorer than is widely assumed. When a band near the centre of the visible spectrum is isolated, the output of a typical tachistoscope lamp takes approximately 18 ms to reach 90% of its asymptotic value; the time to decay to 10% is also typically 18 ms and we demonstrate conditions under which the decaying trace remains visually effective against a dark field for more than 40 ms after the nominal offset of the lamps.

Many reports of tachistoscopic experiments published in the last two decades must be quantitatively in error; and we provide examples of experiments where qualitative conclusions may have been drawn invalidly.     

A neurophysiologic model for aggressive behavior in the cat

A neurophysiologic model for aggessive behavior in the cat is proposed. Stimulus-bound and seizure-bound aggression was evaluated in relation to limbic and basal ganglia induced seizures (after-discharges). Electrically induced limbic and basal ganglia afterdischarges were used because they are known to implicate septohypothalamic sites from which aggression can be elicited by direct stimulation. The occurrence of behavioral aggression is correlated with the discharge characteristics of a single discharging system and with two interacting discharging systems. Aggression is composed of autonomic and somato-motor components which poses relatively low and high thresholds, respectively, for their activation. Aggression occurring during a combined septum and amygdala discharge was more intense and prolonged than with a septum discharge alone. Participation of a slow frequency discharging basal ganglia system activated seizurebound aggression in an otherwise nonaggressive limbic seizure. The limbic and basal ganglia stimulations and after-discharges lowered the excitability threshold of the aggression system and made it more vulnerable to being activated by external stimuli, such as visual and auditory stimuli. These observations are reminiscent of patients with aggressive behavior associated with psychomotor seizures.     

Acquisition and discrimination of appetitively and aversively conditioned heart rate responses in rhesus monkeys

This report describes the acquisition of a conditional heart rate response to both classical aversive and appetitive conditioning in eight rhesus monkeys(Macaca mulatta). The behavioral paradigm consisted of two discrete one minute tones followed by the corresponding unconditional stimuli,i.e., electric shock or Purina monkey chow. A third tone followed by neither food nor shock served as a discriminative stimulus (DS). The conditional heart rate responses developed in two phases. The first phase was characterized by similar responses to both conditional stimuli and the DS. Control heart rate rose during this period. During the second phase, control heart rate decreased (five animals), the DS response disappeared, and different conditional heart rate patterns to food and shock emerged. The existence of distinct conditional response patterns indicates probable differences in the autonomic nervous regulation of the heart during aversive and appetitive conditioning.     

Ethanol’s influence on the stimulus level required to evoke an orienting response in goldfish

In goldfish the heart rate orienting response to periodic photic stimuli was measured by a specially designed computer that also regulated the intensity of the stimuli to maintain the response. When ethanol was administered, the fish then exhibited orienting responses to less intense stimuli; this increased excitability was maintained for the duration of all tests(i.e., a maximum of 26 hours). There also seemed to be a residual increase of excitability lasting as long as 7 days after the ethanol was administered.     

A multipurpose activity platform utilized in the open-field setting

An automated multipurpose activity platform (MAP) that can be used to measure activity in the horizontal plane is described. Detection of the position of a small-bodied animal is based on completion of an electronic circuit in one or several cells of a 21 by 21 matrix below the floor. The MAP is constructed on the basis of an 11 by 11 matrix, but, through electronic averaging, operates functionally on the basis of a 21 by 21 matrix. The MAP has no built-in data storage facility and needs to be interfaced with a recording system. The system has been successfully utilized in measuring open-field activity of the rats.