Personality and modulation of the startle reflex by emotionally-toned filmclips

Several researchers have found that pleasant foreground stimuli attenuate the eyeblink component of the startle reflex while unpleasant foreground stimuli potentiate it. The effects of personality factors on such modulation of the eyeblink response, as measured by electromyographic (EMG) activity in reaction to loud acoustic startle probes, were examined in subjects viewing emotionally-toned (pleasant, unpleasant and neutral) filmclips. During the main part of the experiment, introverts had higher baseline EMG activity and lower response probability than extraverts; no differences were observed at the beginning of the experiment, during an acclimatization session. Reflex modulation, as measured by response latency, was influenced by the Psychoticism (P) factor of the Eysenck Personality Questionnaire: subjects high on P showed longer latencies to eyeblink onset when probed during viewing of pleasant filmclips than subjects low on this dimension; no significant differences were observed between subjects low and high on P for neutral and unpleasant filmclips. No influence of personality factors was found on affective modulation as measured by response amplitude/magnitude. The results are discussed in relation to Gray's and Eysenck's theories of personality.     

Effect of adrenocorticotropic hormone on conditioned avoidance in rats interpreted as state-dependent learning.

Rats were given one training trial that was followed 2 days later by one test trial in a "step-out" passive avoidance task. Each rat was injected with either adrenocorticotropic hormone (ACTH) or placebo before training and before testing. Four groups of rats were used, representing the 4 possible training-testing injection combinations: placebo-placebo, placebo-ACTH, ACTH-placebo, and ACTH-ACTH. ACTH given in testing increased avoidance for subjects that had received ACTH in training and decreased avoidance for those that had received placebo in training.     

Book review

EVANS, R. M. The Perception of Color. New York: Wiley and Sons. 1974. Pp. xii + 248. £ 8.10.

ROSS, H. E. Behaviour and Perception in Strnge Enviroment. London: George Allen and Unwin. 1974. Pp. 171. £ 3.95. (Hardback), £ 1.95. (Peperback).

COOPER, J. R. BLOOM, F. E. and ROTH, R. H. The Biochemical Basis of Neuropharmacology. 2nd Ed. New York and London: Oxford University Press. 1974. Pp. 272. £ 2.50.

JOHNSON, F. N. (Ed.) Lithium Research and Teerapy. London: Acakemic Press. 1974. Pp. 570. £ 13.50.

GERGG, L. W. (Ed.) Cognition in Lerning and Memory. New York: Wiley. 1972. Pp. vii + 263. £ 5.85.

SCHIEFELBUSCH, R. L. and LLOYD, L. L. Language Perspectives-Acquisition, Retardation and Intervention. Macmillan: Baltimore, 1974. Pp 670. £ 7.95.

CHOMSKY, C. The Acquisition of Syntax of Syntax in Children form 5 to 10. Cambridge, Massa-chusetts: M. I. T. Press. 1969. Pp. 126.

Annual Review of Psychology. Vol. 25. Palo Alto, California: Annual Reviews Inc. 544 PP. $ 12.50.

HARRISON, B. Meaning and Structure: An Essay in the Philosophy of Language. New York: Harper and Row. 1972. Pp. 318. £4.65.

MACKINTOSH, N. J. The Psychology of Animal Learning. Academic Press. 1974. Pp. 730. £ 8.00.

BURES, J., BURESOVA, O. and KRIVANEK, J. The Mechanism and Application of Leao's Spreading Depression of Electroephalagraphic Activity. New York: Academic Press. 1974. Pp. 410. £ 14.15.

SOLSO, R.L. (ED.). Theories in Cognitive Psychology: The LOyola Symposium. Potomac, Maryland: Lawrence Erlbaum associates. 1974. £ 7.95.

MURDOCK, B. B. Jr. Human Memory: Theory and Data. Potomac: Erlbaum (distributed by Wiley). 1974. Pp. 362. £ 6.85.

REED, S. K. Psychological Process in Pattern Recogntion. New York: Academic Press. 1973. $ 13.95.

RABBIT, P. M. A. and DORNIC, D. (Eds). Attention and Performance V. London: Academic Press. 1975. Pp. 732. £ 16.00.     

Basic objects in natural categories

Categorizations which humans make of the concrete world are not arbitrary but highly determined. In taxonomies of concrete objects, there is one level of abstraction at which the most basic category cuts are made. Basic categories are those which carry the most information, possess the highest category cue validity, and are, thus, the most differentiated from one another. The four experiments of Part I define basic objects by demonstrating that in taxonomies of common concrete nouns in English based on class inclusion, basic objects are the most inclusive categories whose members: (a) possess significant numbers of attributes in common, (b) have motor programs which are similar to one another, (c) have similar shapes, and (d) can be identified from averaged shapes of members of the class. The eight experiments of Part II explore implications of the structure of categories. Basic objects are shown to be the most inclusive categories for which a concrete image of the category as a whole can be formed, to be the first categorizations made during perception of the environment, to be the earliest categories sorted and earliest named by children, and to be the categories most codable, most coded, and most necessary in language.