Effects of food deprivation and reinforcement magnitude on conditioned suppression

In Experiment I, the responding of rats lever pressing on a variable-interval schedule for sucrose solution was partially suppressed by a variable duration conditioned stimulus followed by shock. When food deprivation was increased, response rates during and before the conditioned stimulus increased monotonically. Varying the concentration of sucrose across blocks of sessions or from session to session in a semi-random sequence had little effect on response rates either before or during the conditioned stimulus. With a fixed sequence of increasing concentrations across a five-session block, increased concentration produced much more rapid increases in response rates before than during the conditioned stimulus. In Experiment II, rats were presented with the same sequence of increasing concentrations across a five-session block. When tested at 80% body weight, response rates increased rapidly as concentration increased, but at 100%, body-weight rates increased only slightly. The effect of a change in body weight in Experiment II thus mimicked the effect of the conditioned stimulus in the latter part of Experiment I. These findings support the view that the effect of a pre-aversive conditioned stimulus is similar to that of a change in food deprivation, but unlike that of a change in reinforcement magnitude.     

Book reviews

Hamilton, Vernon and Veronon, Magdalen D. (Eds). The Development of Cognitive Processes. London and New York: Academic Press. 1976. Pp. 772. £21.00. ISBN 0 12 321750 4.

Miller, G. A, and Johnson-Laird, P. N. Language and Perception. Cambridge University Press. 1976. Pp. viii + 760. £12.50. ISBN 0 521 21242.

Neisser, U. Cognition and Reality. San Francisco: Freeman. 1976. pp. 230. Hardback $11.00; paperback $4.95. ISBN 0 7167 04781.

Norman, D. A. Memory and Attention. Second edition. New York: Wiley. 1976. Pp. 262. £8.45.

Hammond, K. R. and Joyce, C. R. B. (eds). Psychoactive Drugs and Social Judgment: Theory and Research. New York and London: Wiley. 1975. Pp. 278. £9.25. ISBN

Fodor, J. D. Semantics : Theories of Meaning in Generative Grammer. Sussex: Harvester Press. 1977. Pp. 225. £12.95. ISBN 0 85527 500 6.

Plomp, R. Aspects of Tone Sensation. London: Academic Press. 1976. Pp. id + 167. £6.50. ISBN 0 12 558350 8.

Fite, K. V. The Amphibian Visual System. London: Academic Press. 1977. Pp. 374. £20.95. ISBN 0 12 257450 8.

Eliot, J. and Salkind, N. J. Children's Spatial Development. Springfield, Illinois: Charles C. Thomas. 1975. $23.50. Pp. 296. ISBN 0398 03210 6.

Wong, R. Motiviation : A Biobehavioral Analysis of consummatory Activities. London: Collier-Macmillan. 1976. Pp. 326. £ 4.95. ISBN 0 0242 9400 4.     

On the limits of Kagan’s impulsive reflective distinction

A logical analysis is made of the Matching Familiar Figures (MFF) Test on the basis of which children have been classified as "impulsive" or "reflective." The reflective strategy is implicitly preferred to the impulsive because the reflective child makes fewer errors though generally taking longer to make his first response. We show that the test allows the choice of a number of "game plans" and speed-accuracy tradeoffs which in practice may not be very different. Error rates may not indicate perceptual sensitivity, in any case, since sensitivity and response factors may be confounded in the error rate. Using a visual running-memory-span task to avoid the inherent difficulties of the MFF test, we found that children previously classified on the basis of that test as impulsive or reflective did not differ in recognition accuracy but did differ in response bias and response latency. Accuracy and bias are estimated by way of Luce's choice theory (Luce, 1963), and the results are discussed in those terms.     

Overselectivity,developmental level,and overtraining in autistic and normal children

Thirteen autistic children were compared to 13 normal children, matched to them in mental age, on performance of a visual discrimination task. Form, color, and size were relevant and redundant cues. The groups did not differ significantly in mean trials to reach criterion or in breadth of learning, and both groups increased their breadth of learning after 50 trials of overtraining. Form was preferred to color and size by both autistic and normal children. Within each group, rank on mental age was highly correlated with rank in breadth of learning. Verbal and nonverbal autistic children did not differ in breadth of learning or in dimensional preference. Even nonverbal autistics equaled the performance of their normal controls. Our results suggest that overselective attention is better understood as part of a general developmental lag in cognition in autistic children than as a specific deficit underlying psychotic behavior.This research was supported in part by NIMH Grant 11440, O. I. Lovaas, principal investigator. The authors thank Dr. Lovaas and Dennis C. Russo for their helpful criticisms of an earlier draft.     

Modification of the rat's acoustic startle response by antecedent visual stimulation.

Male hooded and albino rats were exposed to a light flash followed at various temporal intervals by a startle-eliciting 117 db. (re 20 muN/m2) burst of white noise. The visual stimulus engendered startle response inhibition (maximally when the lead time was 64-250 msec) as well as startle response latency reduction (maximally when the lead time was 2-8 msec). The temporal functions for the effects of visual stimuli paralleled those previously reported for startle modification by acoustic events. Further study revealed that, given optimal lead times, inhibition is produced reliably by weaker visual stimuli (3 X 10-6 cd-sec/cm2) than latency reduction (3 X 10-4 cd-sec/cm2). This differential sensitivity to visual stimuli is also analogous to previously reported findings for events in the acoustic environment. It reveals that the neural mechanisms that mediate latency reduction and inhibition can be engaged by either acoustic or visual stimulation.