Positive interaction (induction) in multiple variable-interval, differential-reinforcement-of-high-rate schedules

The effect of increases in the rate of responding in one component of a multiple schedule upon the rate of responding in a second component was investigated. Pigeons were exposed to a multiple schedule where both components were initially variable-interval schedules having the same parameter value. After rate of key pecking stabilized, one component was changed to a schedule that differentially reinforced high rates of responding. Rate of reinforcement in this varied component was adjusted to remain equal to rate of reinforcement in the constant (variable-interval) component. Four of five pigeons showed a maintained increase in rate of responding during both the constant and varied components, even though rates of reinforcement did not change.     

Short-term visual memory and pattern masking

The results of two experiments involving the matching of unfamiliar, nameless shapes (Gibson forms) indicated that a visual representation of a brief (30-100 ms) stimulus survives in a Short-Term Visual Memory (STVM) for 6 s or more after the onset of a pattern mask. On the basis of these results a possible alternative to Sperling's (1967) model for short-term memory for visual stimuli was presented. In this model it is assumed that recognition processes occupy several hundred milliseconds and continue after the arrival of the mask using the information available in STVM.     

Error patterns in a chord keyboard response task

Errors in a serial choice-reaction time experiment employing two-finger chord responses to alphabetic stimuli are shown to be distributed in a significantly non-random fashion. Two factors are postulated which are relevant to prediction of the error response. These are the presence or absence of a common finger, and the difference in finger separation, between the actual and the required response. It is suggested that the chord response is coded in terms of a pattern (the distance between the two response components). Responses which mirror the correct response about the centre of the hand are also shown to be significantly more frequent.     

Reduction of anxiety in genetically timid dogs

In behavior studies of genetically timid and normal dogs it was possible to focus on nervous non-performing animals in a search for agents which might attenuate the overriding anxiety which causes these animals to become rigid, aversive-avoiding or bizarre in the presence of humans. Of the drugs tested, chlordiazepoxide (Librium, Roche), 75 to 200 mg per dog per day, was most effective in alleviating the anxious condition. Sometimes the drug had the effect of getting the animal over a “threshold” so that he continued to perform (bar-pressing) indefinitely after once started through the aid of chlordiazepoxide. This is considered an example of both schizokinesis and autokinesis which Gantt first described and associated with drug action utilizing conditional response techniques.     

Auditory evoked brain responses: Intensity functions from bipolar human scalp recordings

Average evoked brain responses were computed from four simultaneous recordings during binaural tone stimulation at 10 intensity levels. Amplitudes and latencies were measured for the prominent components, and linear regression coefficients were computed. The results indicate that the sensitivity of the evoked response to stimulus intensity is dependent upon the selection of the appropriate measure. Linear amplitude functions were demonstrated. Additional research relating these responses to psychophysical measures is suggested.