Does nondirectional signalization of target distance contribute to navigation in the Morris water maze?

The possibility that rats can navigate in the Morris water maze by reducing the difference between the memorized platform scene and the current sensory input was tested in nine blind rats. A computerized videosystem monitored the rats' movements in the pool and converted the rat-target distance into tones the frequency of which increased in 64 equal steps from 120 Hz at 128 cm to 7680 Hz at 0 cm. During 15 days of training to find a fixed platform position from different starting points (12 trials per day) average escape latencies decreased from 39.0 to 25.4 s. The performance significantly deteriorated when the acoustic distance signalization was omitted and/or when the target position was changed form trial to trial. It is concluded that blind rats solved the task by simultaneously employing search strategy based on position responses, mapping using acoustic background beacons, and distance reduction navigation. It is argued that the various strategies are additive and that their relative significance depends of the conditions of the experiment.     

Intentional and incidental visual memory as a function of cognitive level and color of the stimulus

Performance of two groups of youngsters, educable mentally retarded (CA 15-5; MA 11-4; IQ 74.3) and those of average ability (CA 10-5; MA 11-3; IQ 109.1) was compared for intentional and incidental visual memory as a function of cognitive level and color of the stimulus. Nonretarded subjects performed significantly better than the retarded ones of equal MA. Both groups performed better with a color than black-white card, and both groups did better on the tasks involving intentional rather than incidental memory.     

From front line to home front: a study of secondary traumatization.

While the long-term effects of combat trauma on veterans have been studied extensively, its impact on veterans' wives has yet to be investigated. This study examined the implications of combat-induced psychopathology--wartime combat stress reaction (CSR) and current posttraumatic stress disorder (PTSD)--in a sample of 205 wives of Israeli combat veterans of the 1982 Lebanon war. Results show that both CSR and PTSD were associated with increased psychiatric symptoms in the wives. In addition, current PTSD was particularly found to contribute to impaired social relations among veterans' wives in a broad range of contexts, from inner feelings of loneliness, through impaired marital and family relations, and extending to the wider social network. Implications of these findings for treatment and further research are discussed.     

Individual gustatory reaction times to various groups of chemicals that provoke basic taste qualities

Reaction times (RTs) to four groups of substances that provoke different taste qualities were measured. Measurements for all substances with the same taste, equalized in perceived intensity and provoking a very strong taste, were made concurrently for each subject. The comparisons were made on the individual level. No significant differences in RTs to substances with the same taste quality were found. When the factor of perceived intensity is kept constant, no effect of the stimulus chemical composition on RTs seems to be present. RTs to stimuli with different tastes differ significantly, the shortest being to salt and the longest to bitter. The difference in RTs for sour and sweet substances is small, and the subjects were not all alike in terms of the order of RTs with respect to these stimuli.     

Using item-specific instructional information in achievement modeling

The problem of detecting instructional sensitivity (item basis) in test items is considered. An illustration is given which shows that for tests with many biased items, traditional item bias detection schemes give a very poor assessment of bias. A new method is proposed instead. This method extends item response theory (IRT) by including item-specific auxiliary measurement information related to opportunity-to-learn. Item-specific variation in measurement relations across students with varying opportunity-to-learn is allowed for.This paper was presented at the 1987 AERA meeting in Washington, DC. This research was supported by grant OERI-G-86-003 from the Office of Educational Research and Improvement, Department of Education. The author thanks Michael Hollis and Chih-fen Kao for valuable research assistance, and appreciates valuable comments made by an anonymous reviewer.     

Emotions and emotional communication in infants

Important advances have recently been made in studying emotions in infants and the nature of emotional communication between infants and adults. Infant emotions and emotional communications are far more organized than previously thought. Infants display a variety of discrete affective expressions that are appropriate to the nature of events and their context. They also appreciate the emotional meaning of the affective displays of caretakers. The emotional expressions of the infant and the caretaker function to allow them to mutually regulate their interactions. Indeed, it appears that a major determinant of children's development is related to the operation of this communication system. Positive development may be associated with the experience of coordinated interactions characterized by frequent reparations of interactive errors and the transformation of negative affect into positive affect, whereas negative development appears to be associated with sustained periods of interactive failure and negative affect.     

Hypothesizing and evidence-gathering: the nexus of understanding

Prior discussion of hypothesizing as a session "guideline" has not fully clarified the derivation of hypotheses. Reviewing relevant philosophy of science literature, the authors develop the notions of evidence and evidence-gathering in systemic family therapy. The authors claim evidence-gathering and hypothesizing are interdependent, reciprocal elements of scientific understanding. The structure of evidence is described along with practical and qualitative rules for collecting and using evidence. This model is applied to a case example illustrating the logic of clinical process. Implications are discussed for family therapy training and supervision.