Vocal changes in stutterers and nonstutterers during monotoned speech

For years, reports have circulated that stutterers experience marked decrements in their stuttering when they speak or read in monotone. Wingate has suggested that the ameliorative effects of various novel speaking conditions on stuttering can be attributed to modifications in vocalization induced by such conditions. The present study was conducted to see whether this explanation would extend to monotoned speech as well. Ten teenage and adult stutterers and 10 normal speakers were tested in control and monotone reading conditions. Dependent measures were the frequencies of disfluency and stuttering, fundamental frequency, fundamental frequency standard deviation, vocal SPL, vocal SPL standard deviation, and fluent reading rate. Only within-group statistical comparisons were made, because members of the two groups could not be matched pairwise along critical vocal parameters. The major findings of this study indicated that across the two conditions, both groups significantly reduced their fundamental frequency, fundamental frequency standard deviation, vocal SPL and vocal SPL standard deviation. Only the stutterers exhibited a significant decrement in disfluency and stuttering. The normals did not evince enough disfluency in the control condition for a reduction to occur during monotoning. Neither group effected a reduction in fluent reading rates. These and other findings and interpretations are discussed relative to Wingate's modified vocalization hypothesis.     

Post-Conditioning Devaluation of an Instrumental Reinforcer has no Effect on Extinction Performance

The extent to which a representation of the reinforcer controls an instrumental response can be assessed by studying the effect of post-conditioning changes in the reinforcer value. In the first experiment rats were trained to press a lever for sucrose pellets on a variable-interval (VI) schedule. The sucrose was subsequently devalued by pairing with Lithium Chloride (LiCl). This had no effect on lever pressing in extinction, although it profoundly reduced reacquisition responding and consumption. In Experiment II rats were trained to shuttle between the two distinctive chambers of a choice-box, in which lever pressing was reinforced in one chamber by sucrose and in the other chamber by food pellets programmed on independent VI schedules. A LiCl-induced taste-aversion was conditioned to the sucrose, and although this markedly affected reacquisition, extinction responding in the sucrose chamber and chamber preference were unaffected. These results indicate that instrumental performance can be independent of the current value of the reinforcer, and are discussed with reference to stimulus-response theory and second-order Pavlovian conditioning.     

Outdoor enclosures for feralizing rats and mice

Rationales for the naturalistic study of rattus and mus in outdoor enclosures are well known but rarely transformed into practice. This paper describes the materials, construction details, and operational procedures for rat and mouse pens that are easily and inexpensively built and maintained. The suggestion here is that outdoor enclosures offer meaningful views of rodent behavior not accessible in traditional laboratory situations.     

Enhancement of off-key pecking by on-key punishment

Under a variable-interval food reinforcement schedule, some of a pigeon's pecking responses land on the wall area adjacent to the response key. These off-key pecks increase in frequency when key responses produce shocks and decrease when shock is removed.     

A closed-loop theory of motor learning

Following a discussion of the meaning of the term "skills" and a review of historical influences on their learning, a closed-loop theory for learning simple movements is presented. Empirical generalizations from the literature are stated, and the theory is used to explain them. The generalizations are of 2 classes: learning through the application of knowledge of results, and the effects of withdrawing knowledge of results.