Apparatus accurate delays for auditory feedback experiments

This note describes a way of modifying a tape recorder for producing accurately controllable delays for experiments with delayed auditory feedback. Any value of delay from 80 millisec. to 1.2 sec. can be obtained to the nearest millisec., and the range could be extended by some minor changes. The delay is continuously monitored on a digital electronic timer.     

Continuity effects with alternately sounding tones under dichotic presentation

An experiment is reported in which 10 Ss possessing normal hearing were required to make discriminations of continuity or interruption in a longer less intense signal (Tone A) which alternated in time with a shorter more intense signal (Tone B). The signals were presented dichotically with Tone A at the right ear. Three Tone B frequencies of 300, 1000, and 4000 cps and five Tone A frequencies somewhat near each of the Tone B frequencies were employed. The results demonstrated that as Tone A was nearer to Tone B in frequency, continuity thresholds in Tone A occurred at longer durations of Tone B. The results are discussed in terms of a central neural model.     

Observing responses and discrimination learning

An operant response in the pigeon, whose performance results in exposure to the discriminative stimuli, is described and suggested as an experimental analogue for “observing.” Such an operant response is then used to explore the relationship between observing responses and discrimination learning in a variety of discrimination situations, of progressively increasing complexity. In general, the results support the contention that the development and maintainence of observing responses is closely related to the degree of differential behaviour manifested toward the discriminative stimuli. Certain modifications are suggested in the theoretical formulation underlying the concept of “observing responses.”