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.     

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.     

Averaged occipital responses to stimulation of sites in the upper and lower halves of the retina

Averaged responses of the occipital lobes to flashes imposed along the midline of the upper part of the retina are larger and of shorter latency than responses to flashes imposed on the lower retina. Since reaction times also are shorter when the upper retina is stimulated, this study provides further evidence for the generalization that reaction time varies inversely with amplitude and directly with latency of the evoked response.     

The development of object-permanence: Some studies of existence constancy

Object permanence or existence constancy was one of the phenomena which greatly exercised the philosophical fathers of experimental psychology. The topic has been little studied since. Michotte has described the psychophysics of existence constancy, while Piaget has studied its development. Michotte’s work was restricted to adults while Piaget’s notably lacked careful psychophysical control. The aim of the present study was to bridge the gap between the two, to study the psychophysics of existence constancy in infants. Results showed that there is remarkably little difference between infant and adult as far as psychophysical control is concerned. The major difference seems to be a rate of processing difference. However, changes in processing rate will not account for the development of the concept of object permanence. What seems to be learned is a rule which can override perceptual constancy and nonconstancy in some situations.     

In search of ambiguity

A study of the time required for Ss to perceive the two meanings of ambiguous sentences, supports the following conclusions: (I) Perception time (PT) is a function of the type of ambiguity, three of which are defined in this study. (2) A similar relative function was obtained for thePT in sentences with more than one ambiguity and for sentences with only a single ambiguity. (3) ThePT for finding a single ambiguity in such multiply ambiguous sentences was significantly longer than in singly ambiguous sentences. (4) When one of the interpretations of certain types of ambiguous sentences is less likely than the other (where likeliness is defined in terms of the number of Ss perceiving that inter-pretation first)PT is high. (5) Complexity of the surface and underlying structures (which are defined in transformational grammar) is an important determinant of thePT for surface and underlying structure ambiguities, respectively.