Tests for inhibition after extinction of a conditioned stimulus in the flavour aversion procedure

In four experiments, rats received flavour aversion conditioning followed by extinction. The flavour was then subjected to retardation and summation tests. Experiment 1 showed that reacquisition of an extinguished flavour aversion was retarded with respect to the performance shown by rats for whom the flavour was novel. No retardation was found, however, with respect to a control group that had been given non-reinforced pre-exposure to the flavour. Experiment 2 demonstrated that extinction showed the same sensitivity to the effects of a retention interval as did latent inhibition, consistent with the view that the retardation effect was a consequence of the occurrence of latent inhibition during extinction. An extinguished stimulus was also found to alleviate the response governed by aseparately trained excitor in a summation test (Experiments 3 and 4), but the size of this effect did not exceed that produced by a control stimulus when the procedure used ensured an equivalent aversion to the test excitor in the two cases. These results challenge the proposal that extinction can turn a stimulus into a net inhibitor.     

Discrimination between outcomes in instrumental learning: Effects of preexposure to the reinforcers

In two experiments rats received instrumental training with two response levers, one response being reinforced by sucrose solution and the other by sucrose pellets. Prior to a test session, on which both levers were made available in the absence of reinforcement, the rats were given free access to one of the reinforcers, a procedure known to reduce its value. It was found that the rats responded at a lower rate on the lever that had produced the now-devalued reinforcer, but that this effect was substantial only in rats that had received preexposure to the two reinforcers before instrumental training was begun (Experiment 1). Experiment 2 demonstrated that this effect was obtained only when presentations of the two reinforcers were presented according to an inter-mixed schedule during preexposure. It is suggested that this result constitutes an instance of the perceptual learning effect in which intermixed preexposure to similar events enhances their discriminability.     

Book reviews

Bloom, A. H. The Linguistic Shaping of Thought : A Study of the Impact of Language on Thinking in China and the West. Hillsdale, N.J.: Erlbaum. 1981. Pp. 106. £9.95. ISBN 0 89859 089 2.

Fodor, J. A. Representations : Philosophical Essays in the Foundations of Cognitive Science. Brghton: Harvester. 1981. Pp. 343. £22.50. ISBN 0 85527 977 X.

Sanford, A. J. and Garrod, S. C. Understanding Written Language: Explorations in Comprehension Beyond the Sentence. Chichester: John Wiley & Sons. 1981. Pp. xiv + 224. £ 11.30. ISBN 0 471 27842 4.

Springer, S. P. and Deutsch, G. Left Brain, Right Brain. San Francisco: W. H. Freeman & Co. 1981. Pp. 243. £4.95 (paperback). ISBN 0 7167 1270 9.

Crystal, D. Introduction to Language Pathology. London : Edward Arnold. 1980. Pp. 214. ISBN 0 7131 62759. £5.50.

Hulme, C. Reading Retardation and Multi-Sensory Teaching. London : Routledge & Kegan Paul. 1981. £12.50. Pp. 200. ISBN 0 7100 0761 2.

Liben, I,. S., Patterson, A. R. and Newcombe, N. (Eds). Spatial Representation and Behaviour Across the Life Span. New York: Academic Press. 1981. Pp. 404. ISBN 0 12 447980 4. £17.80.

Coltman, D. Jean Piaget: Experiments in Contradiction. Chicago: University of Chicago Press. 1980. Pp. 310. ISBN 0 226 66779 0. £13.20.

Hofer, M. A. The Roots of Human Behavior. San Francisco: Freeman. 1981. Pp. xiii + 331. Paperback £6.70. ISBN 0 7167 1278 4.     

College Students' Responses to Suicidal Content on Social Networking Sites: An Examination Using a Simulated Facebook Newsfeed

Although Facebook has a peer‐initiated suicide prevention protocol, little is known about users' abilities to notice, recognize, and appropriately interpret suicidal content or about their willingness to intervene. In this study, 468 college students were randomly assigned to interact with a simulated Facebook newsfeed containing content reflecting various suicide risk levels. A larger proportion of those exposed to content reflecting moderate and severe suicide risk noticed, recognized, appropriately interpreted, and endorsed taking action to intervene, as compared to those exposed to content representing no or low risk. Overall, results indicate that college students are responsive to suicidal content on Facebook.     

A Follow-up Study of 53 Suicides Known to a Suicide Prevention Center

ABSTRACT: The operation of the Cleveland Suicide Prevention Center is reviewed, and 53 known suicides during the Center's first four years of operation are discussed. A suicide rate of 288 per 100,000 suggests that persons contacting the Center represented a high suicide risk group. Of the suicides, 57 percent were women. This high proportion of females was statistically significant when compared to the smaller percentage of female suicides for Cuyahoga County, Ohio. Of the persons who committed suicide, 26 percent initiated direct contact with the Center themselves, and none recontacted the Center just prior to death. The question is raised whether contact initiated by another may in itself be suggestive of greater suicidal risk. Some of the practical problems in evaluation and referral are discussed.     

The instrumental overshadowing effect in pigeons: The role of response bursts

Experiment 1 showed that, when reinforcement is delayed by 0.5 sec for pigeons responding on a variable interval schedule, bursts of responses tend to occur during the delay interval. Such bursts are not seen when a signal (illumination of the houselight) fills the delay interval. The higher overall response rate seen with the unsignalled procedure may, therefore, be a consequence of the differential reinforcement of response bursts. Experiment 2 found, however, that the difference between the signalled and unsignalled conditions remained when the signal used was one that was relatively ineffective in suppressing bursts. Experiment 3 found that in some conditions the unsignalled procedure will generate a higher response rate than the signalled procedure even when there is no delay of reinforcement and thus little opportunity for differential reinforcement of response bursts. It is argued that, in addition to any contribution from the differential reinforcement of bursts, these effects also reflect the overshadowing of a response—reinforcer association by the signal that is a more valid predictor of the reinforcer.