Squirrel monkeys were exposed to response-independent, fixed-frequency shock that produced biting attack upon a pneumatic hose. Attacks decreased within and across sessions at low intensities and high frequencies of shock, but increased within and across sessions at higher intensities and lower shock frequencies. Stimuli paired with shock, when presented alone, came to produce biting, and stimuli correlated with shock parameters that produced increases in responding within sessions produced similar increases when presented alone. Further experiments showed that continuing exposure to shock also produced lever pressing or chain pulling, with longer shock exposure again producing higher response rates. Whereas biting generally decreased throughout the intershock interval, manual responding generally increased as shock time approached, but immediately before shock was often suppressed. Following shock, biting attack predominated over manual behavior. The results suggest a possible explanation for the extreme resistance of avoidance behavior to extinction, and may also partially explain the persistence of responding during schedules of response-produced shock. Relationships of the present findings to naturalistic observations of relations between fleeing, freezing, and fighting performances are discussed.

The language of 7 children who had used a cochlear implant for 5 years was evaluated by means of the Clinical Evaluation of Language Fundamentals-3, the Peabody Picture Vocabulary Test-Revised, and the Expressive Vocabulary Subtest of the Test of Word Knowledge. All subjects demonstrated impaired skills relative to normal-hearing children on 1 or more subtests. Variability in performance occurred between subjects and within subjects across subtests. Strengths in semantic skills were evident compared to weaker syntactic and morphological abilities. The nature of the subjects' language impairments is considered with reference to language delay and specific language impairment. The findings support the need for further evaluation of the rate and course of development of language subskills. Investigation of the influences of information processing, and learning styles and strategies, on children's outcomes is also warranted. These findings have implications for implementation of optimal habilitation and education programs for children with cochlear implants.

The discourse skills of four boys with a unilateral hearing impairment (UHI), aged 7·2-10·7 years, were appraised over a 2-year period by examining their oral narrative use. All subjects exhibited delayed narrative skills, including features typical of children with a language disorder. These findings of language difficulties within this population were at variance with previous findings showing that children with UHI do not experience language problems. The subjects' language skills were discussed in relation to their academic performance. The implications of the findings for the process of narrative assessment were also discussed.

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