A comparison of operant licking and lever pressing in the rat

Two groups of rats were trained on a signaled, free-operant, avoidance procedure to lick or to lever press in order to avoid shock while water-deprived or satiated and, in the case of licking, while ingesting deionized water, isotonic saline, or 10% sucrose. The most effective avoidance licking occurred while the rats were water-deprived and ingesting 10% sucrose. Water deprivation level had no effect on lever pressing for shock avoidance. Two other groups of rats were operantly conditioned to lick or to lever press for food pellets while waterdeprived or satiated and, in the case of licking, while ingesting deionized water or 10% sucrose. The most effective licking for food reinforcement occurred while the rats were water-deprived and ingesting 10% sucrose. Water deprivation level had no effect on lever pressing for food reinforcement. The data indicated that effective operant licking must be supported by factors related to water regulation and taste palatability.     

Stimulus-form effectsin recognition memory

In two experiments, recognition memory was tested using memorized lists of items containing from 2 to 32 nominal concepts. Stimulus form was manipulated by using the names of the items on word trials and outline drawings of the items on picture trials. In terms of an information processing stage model of recognition memory, stimulus form affected only an identification or encoding stage of processing. Subsequent memory-search, decision, and response processes were largely the same for all stimuli once the words or pictures were encoded. The results are consistent with the hypothesized role of stimulus form in processes underlying long-term recognition. However, our results are inconsistent with those of a number of studies involving stimulus-form effects in short-term recognition memory.     

Research support from the office of Naval Research

The operation of the Psychological Sciences Division of the Office of Naval Research is described briefly. Guidance is provided for prospective proposers of research to that division.     

Visual timing in hitting an accelerating ball

To investigate the timing of actions relative to events in the environment, we observed subjects leaping to punch a falling ball. We analysed their knee and elbow angles as functions of time for three ball-drop heights, finding that the differences in the functions for the different heights could be explained on the basis that the subjects were gearing their actions to a particular optic variable. This variable specifies the time remaining before contact with an object if the closing velocity is constant; for the falling ball it gives an increasingly accurate estimate of the time-to-contact. Our visuo-moto control model incorporates a delay parameter, the value of which was estimated from the data. In addition, correlations indicated that the knee and elbow were generally quite tightly coupled. The relationship of this task to laboratory tracking tasks and to the timing of actions in everyday life is described.     

From the Editor

Journal of Medical Humanities -     

Mothers' resolution of their children's diagnosis: Organized patterns of caregiving representations

In this paper we examine mothers' representations of one form of trauma to the caregiving system: the experience of receiving a diagnosis of a chronic illness or disability in their child. An interview and classification system was used with 91 mothers of children ages 15–50 months with cerebral palsy or epilepsy. Mothers were classified as Resolved or Unresolved with respect to their child's diagnosis and grouped into subcategories within these major groups. Roughly half of these mothers were classified as Unresolved with respect to their child's diagnosis. Diagnosis type, severity of condition, developmental age, and time since receiving diagnosis were all unrelated to the distribution of Resolved/Unresolved classifications. Patterns of resolution in which cognitive strategies predominated were the most frequent form within the Resolved classification. Findings provide support for the organizational nature of caregiving representations as well as a number of implications for clinical practice.