Economic substitutability of electrical brain stimulation, food, and water.

Concurrent variable-ratio schedules of electrical brain stimulation, food, and water were paired in various combinations as reinforcement of rats' lever presses. Relative prices of the concurrent reinforcers were varied by changing the ratio of the response requirements on the two levers. Economic substitutability, measured by the sensitivity of response ratio to changes in relative price, was highest with brain stimulation reinforcement of presses on both levers and lowest with food reinforcement of presses on one lever and water reinforcement of presses on the other. Substitutability with brain stimulation reinforcement of presses on one lever and either food or water reinforcement for presses on the other was about as high as with brain stimulation for presses on both levers. Electrical brain stimulation for rats may thus serve as an economic substitute for two reinforcers, neither of which is substitutable for the other.     

Decreasing junk-food consumption through the use of self-management procedures: a case study

By using a self-management program, a 25-yr.-old white male was able to decrease the amount of junk food and beverage consumed while increasing the amount of healthier food and beverage ingested during evening snacks. This change was evident at 6 wk. and at a 6-mo. follow-up. Factors contributing to this success were discussed.     

Studies in social influence VI: Is Lenin orange or red? Imagery and social influence

Two experiments dealing with the effects of a majority or a minority source influence, solely on the recognition of a portrait, let us study the generalization of the influence to a portrait symbolically linked to a colour. According to the theory of conversion, the bringing into play of the validation process of the stimulus when the source is a minority should allow such a generalization cognitive association. When the source is a majority, a social comparison process should lead to compliance about the portrait, without any cognitive investigation of the whole stimulus. In the first experiment, four slides were shown successively using material similar to Luchins' (1945) and progressively drawing the portrait of Lenin, with a red-orange background for each phase. The dependant variables are: (1) the drawing, (2) the colour of the background, (3) the after-image. On the two last slides for which the answer ‘Lenin’ is given by the source, changes towards red (and the complementary colour green), in the absence of the source under the minority influence, and changes towards orange under majority influence in the absence of the source are registered. Moreoever, the most significant changes of the colour judgment are due to the subjects who refuse to answer ‘Lenin’ during the interaction. In the second experiment, only the fourth slide, on which Lenin's portrait completely appears is shown. The subjects submitted to majority influence answer ‘Lenin’ more than the control group does, only in the presence of the source and change their judgment on the colour of the after-image towards the complementary of orange in the absence of the source. When the source is a minority a sinificant effect towards the red and its complementary colour is shown.     

Integral processing of visual place and auditory voicing information during phonetic perception.

Results of auditory speech experiments show that reaction times (RTs) for place classification in a test condition in which stimuli vary along the dimensions of both place and voicing are longer than RTs in a control condition in which stimuli vary only in place. Similar results are obtained when subjects are asked to classify the stimuli along the voicing dimension. By taking advantage of the "McGurk" effect (McGurk & MacDonald, 1976), the present study investigated whether a similar pattern of interference extends to situations in which variation along the place dimension occurs in the visual modality. The results showed that RTs for classifying phonetic features in the test condition were significantly longer than in the control condition for the place and voicing dimensions. These results indicate a mutual and symmetric interference exists in the classification of the two dimensions, even when the variation along the dimensions occurs in separate modalities.     

A look at social support patterns

The issue of how to provide support for patients with a life-threatening illness continues to be a problem for pastors and chaplains. The authors discuss the significance and reasons for looking at the present day social support patterns as an unnatural problem. Unless the unnatural nature of support in the modern medical setting is understood pastors and chaplains can miss the target on answering the question of how to provide support. The authors conclude the article by addressing this question from the position of reserving the unnatural nature of providing support.Dr. Bergen is Professor of Psychiatry, Dartmouth Medical School, Hanover, NH 03755. Dr. Nelson is affiliated with the Chaplain Service, Veterans Administration Center, White River Junction, VT 05001 and Assistant Professor of Clinical Psychiatry, Dartmouth Medical School.     

Acquisition and extended retention of a conditioned taste aversion in preweanling rats

The time course of memory decay for infant rats may shed light on the processes responsible for infantile amnesia. A taste aversion conditioning procedure appropriate for both neonatal and adult rats was employed in four experiments to investigate the ontogeny of extended retention. In Experiment 1, rats trained at 1, 10, 20, or 60 days of age were tested for retention of the taste aversion 25 days later. At testing, only those rats conditioned when 20 or 60 days old demonstrated significant taste aversions. Experiments 2 and 3 established that rats 14-15 days old and older were able to retain significant taste aversions following a 25-day retention interval. Younger rats did, however, acquire and retain the aversion for several days and showed a gradual retention loss over progressively longer retention intervals (Experiment 4). These findings suggest that preweanling rats demonstrate initial consolidation, storage, and retrieval of conditioned taste aversions. It is only after this initial period that retention deficits become evident.