The overshadowing of background stimuli: Some effects of varying amounts of training and ucs intensity

Two experiments investigated the capacity of a nominal CS to overshadow background stimuli. Rats received CS-shock pairings in one compartment of a double compartment apparatus. After training the shock compartment was represented, but in the absence of both the CS and shock. Overshadowing was then assessed by measuring rats' latency to enter this compartment. If rats readily entered the shock compartment this indicated that the background cues in that compartment had acquired little or no associative strength during training, and overshadowing was therefore inferred. If however rats avoided the shock compartment, then this indicated that the background stimuli must have become aversive during training, and overshadowing could not then be inferred. In both experiments it was found that the capacity of a CS to overshadow background stimuli was directly related to the amount of training given. The experiments also showed that this capacity is inversely related to shock intensity. The results are discussed in terms of Rescorla and Wagner's (1972) model of conditioning.     

Learning capacities during sleep: A preliminary study in a group of schizophrenic inpatients

The relationship between sleep and learning processes is analysed in a sample of schizophrenic patients, starting from more recent hypotheses about the function of REM sleep in learning and memory processes. This is done by means of two experiments: in the first AA. evaluate the possibility to elicit a simple motor conditional reflex acquired during daytime in different sleep stages. With the second experiment daytime learning performances are evaluated with and without a reinforcement administered during REM sleep. Results for the first experiment underline a qualitative difference between REM and nREM sleep in a reflexological perspective. In nREM sleep the conditional response is better maintained than in REM sleep. The second experiment confirms the possibility to improve daytime learning performances after an additional presentation of learning material in REM. The joint study of sleep abnormalities and learning and cognitive impairment in schizophrenic patients is finally suggested.     

A device for measuring patterns of locomotor behavior in the earthworm

A simple device capable of eliciting and detecting earthworm locomotor activity is described and its use outlined. Movement is recorded as an animal crawls in a spoked, revolving wheel. The wheel permits peristaltic crawling, yet restricts the type and timing of other movements. As a result, records of activity differentiate the rate and patterning of peristaltic crawling from changes in bodily position.     

A technique for converting from intravenous drug self-administration to liquid reinforcement

A rapid inexpensive technique for changing from intravenous drug self-administration (DSA) to liquid reinforcement is described. Utilizing a standard peristaltic-type infusion pump typically used in DSA experiments and a specially designed drinking cup, the changeover from intravenous DSA to liquid reinforcement can be accomplished in a few minutes at a cost of less than $10.     

Memory for music

Subjects created imaginal interpretations of classical music passages in accordance with themes which were either concrete and comprehensible or abstract and difficult to comprehend. Recognition memory for the musical passages was found to be superior in the former condition. The results support the hypothesis that meaningful interpretation of stimulus material is a major determinant of memory accuracy. The implications of the results for comparisons of music and language are also discussed.     

Sex and cultural differences in the factorial structure of the self-directed search

Holland's Self-Directed Search was administered to 247 male and 252 female high school students, aged 16 to 18 years, attending state schools in New Zealand. Principal factor analysis was used in an attempt to identify six orthogonal factors analogous to Holland's six personality types. The Social and Enterprising scales could not be split into two factors in either sample, and the Investigative and Realistic scales defined a single factor for the female students. Computed distances between pairs of the six personality types in five dimensional factorial space were compared with the relative ordering of the distances expected from Holland's hexagonal model. The positions of the types in space corresponded more closely with the model for the males than they did for the females. The results, in conjunction with those of similar studies in Israel and the United States, imply that the correspondence between some summary codes on the SDS and existing occupational classifications based on Holland's types may be less than perfect, particularly for females. Also, care should be taken when using codes on the SDS to calculate Holland's indices of “consistency,” especially for females.     

Attention demands of movements as a function of their duration and velocity

The attention demands of initiating and controlling discrete movements were examined as a function of their movement time (MT) and average movement velocity. Experiment 1 showed that the attention required to execute a movement decreased as MT decreased, although Experiment 2 through independently manipulating MT and movement velocity, revealed that movement velocity is the key determiner of attention demands rather than MT. The attention demands of preparing a high velocity movement are greater than during its execution with the reverse being the case for relatively slow velocity movements. The results are compatible with the view that it is the initiation of error corrections that are attention demanding (Keele 1973).