Laboratory control of thumbsucking by withdrawal and re-presentation of reinforcement

A 5-year-old boy was shown cartoons, and punished for thumbsucking during alternate cartoons by turning off the cartoons for as long as his thumb remained in his mouth. Thumbsucking weakened during such periods. During alternate periods of uninterrupted cartoons, thumbsucking promptly recovered, suggesting a quick discrimination process. Two other 5-year-old boys were shown the same cartoons; withdrawal of the cartoons was made contingent upon thumbsucking for one, and randomly yoked for the other. Then their roles were reversed. Contingent withdrawal and re-presentation of the cartoons controlled thumbsucking rate; yoked withdrawal and re-presentation did not.     

Training of fast tapping with reduction of kinaesthetic, tactile, visual and auditory sensations

Five subjects were trained to tap on a light Morse-key during nerve compression block. The training sessions lasted for 40 sec., with a 5 sec. rest after the first 20 sec. work period. The group learning curve reached 89.5 per cent. level of normal performance by the eighth training session. In the ninth, the testing session, subjects tapped with visual and auditory sense reduction superimposed on the kinaesthetic and tactile impariment of the training condition. Performance in the testing session reached 40.9 per cent. of normal.

The sixth subject was trained in the same task as the other five subjects, but the training condition included elimination of cues from all four sensory channels. He reached 79.09 per cent. of his normal tapping performance in the seventh session.

These results show that the motor skill of tapping can be relearned in the absence of kinaesthetic cues. Furthermore when the subject has no conscious knowledge of any peripheral sensory cues connected with the ongoing motor activity, learning can nevertheless take place. These findings lead to the hypothesis, that skilled motor activity can be monitored by central processes alone.

During the training sessions subjects showed a tendency of tapping in groups of gradually increasing length. It is hypothesized that increased number of taps forming a group gives an indication to the possible mode of action of these central processes.     

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.     

The relative intelligibility threshold for one's own name compared with other names

Two recent experiments (Moray, 1959; Oswald, Taylor and Treisman, 1960) have shown that in dichotic listening, and in sleep one's own name seems to be responded to selectively. We have shown for 10 subjects, each listening binaurally to the same recording of a list of their names repeated at random 10 times, and masked by noise, that the subject's own name had a significantly lower threshold than other names. The effect we found was not significantly different from the one found by Oswald et al. during sleep and by Moray for the dichotic situation.

These three experiments taken together suggest that the same pattern-analysing mechanism is involved in normal listening, dichotic listening to the rejected message, and in discrimination during sleep.