Expectancy in Educable Subnormal Children and Their Normal Mental Age Controls

Abstract

The long reaction times of mentally subnormal children have commonly been attributed to an inability to build up an adequate preparatory set. The experiment reported attempted to test this suggestion by comparing the ability of normal and subnormal children to anticipate a regularly occurring event. The performance of educable subnormal (ESN) children was found to be inferior to that of normal children matched on mental age (NMA) both in terms of the accuracy and the variability of their anticipations. However, this inferiority disappeared when visual input was restricted to the relevant events. It is concluded that ESN children suffer both in the accuracy and in the variability with which they estimate time intervals. It is suggested that these deficits may be mediated either by a relatively high level of distractability or by a relatively low level of arousal.

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References

Baker

C. H.

(1962a). On temporal extrapolation. Canadian Journal of Psychology 16, 37–41.

Baker

C. H.

(1962b). Probability of signal detection in a vigilance task. Science (New York) 136, 46–7.

Baumeister

A. A.

Hawkins

W. F.

(1966). Variations of the preparatory interval in relation to the reaction times of mental defectives. American Journal of Mental Deficiency 70, 689–94.

Baumeister

A. A.

Hawkins

W. F.

Kellas

(1965). Reaction speed as a function of stimulus intensity in normals and retardates. Perceptual and Motor Skills 20, 649–53.

Baumeister

A. A.

Kellas

(1968). Reaction time and mental retardation. International Review of Research in Mental Retardation Ellis

N. R.

New York: Academic Press Vol. 3.

Baumeister

A. A.

Ward

L. C.

(1967). Effects of rewards upon the reaction times of mental defectives. American Journal of Mental Deficiency 71, 801–5.

Clausen

(1966). Ability structure and subgroups in mental retardation London: Macmillan.

Deese

(1955). Some problems in the theory of vigilance. Psychological Review 62, 359–68.

Follini

Sitkowski

C. A.

Stayton

S. E.

(1969). The attention of retardates and normals in distraction and non-distraction conditions. American Journal of Mental Deficiency 74, 200–5.

10.

Heal

L. W.

Johnson

J. R.

Jr. (1970). Inhibition deficits in retardate learning and attention. International Review of Research in Mental Retardation Ellis

N. R.

New York: Academic Press Vol. 4.

11.

Karlin

(1959). Reaction time as a function of foreperiod duration and variability. Journal of Experimental Psychology 58, 185–91.

12.

Klemmer

E. T.

(1956). Time uncertainty in simple reaction time. Journal of Experimental Psychology 51, 179–84.

13.

Klemmer

E. T.

(1957). Simple reaction time as a function of time uncertainty. Journal of Experimental Psychology 54, 195–200.

14.

McNutt

J. H.

Melvin

K. B.

(1968). Time estimation in normal and retarded subjects. American Journal of Mental Deficiency 72, 584–9.

15.

Michon

J. A.

(1967). Timing in temporal tracking The Netherlands Institute for Perception. RVO-TNO.

16.

Sandler

(1955). A test of the significance of the difference between the means of correlated measures, based on a simplification of student's. T. British Journal of Psychology 46, 225–6.

17.

Semmel

M. I.

(1965). Arousal theory and vigilance behaviour of educable mentally retarded and average children. American Journal of Mental Deficiency 70, 38–47.

18.

Snodgrass

J. G.

Luce

R. D.

Galanter

(1967). Some experiments on simple and choice reaction time. Journal of Experimental Psychology 75, 1–17.

19.

Welford

A. T.

(1968). Fundamentals of skill London: Methuen.