Sex Differences in Exploration: Toward a Theory of Exploration

Lester, David

doi:10.1007/bf03393689

Cited by 40 publications

(16 citation statements)

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“…This experiment indicates that rats who defecate do tend significantly to have extreme activity scores, and this phenomenon is in accord with the fearmotivated theory of exploration proposed by Lester (1967). This result may account for the inconsistent correlations reported by other workers between activity and defecation.…”

Section: Discussionsupporting

confidence: 87%

“…Lester (1967) proposed a theory of exploration in which mild increases in the fear level of an organism increases the exploratory tendencies of that organism. As the fear level of the organism rises still further the exploratory tendencies of the organism begin to decrease until, at very high fear levels, avoidance behavior is shown.…”

Section: It Was Predicted From a Fear-motivated Theory Of Explorationmentioning

confidence: 99%

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Two tests of a fear-motivated theory of exploration

Lester

1968

Psychon Sci

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It was predicted from a fear-motivated theory of exploration that defecating rats should show extremes of activity in an open-field test. This prediction was supported.A n explanation of a reported sex difference in exploratory behavior that was based on this fear-motivated theory of exploration was not supported. Lester (1967) proposed a theory of exploration in which mild increases in the fear level of an organism increases the exploratory tendencies of that organism. As the fear level of the organism rises still further the exploratory tendencies of the organism begin to decrease until, at very high fear levels, avoidance behavior is shown. If defecation is an index of fear level and if defecation occurs at both intermediate and high fear levels, then defecating rats will show either maximum exploratory behavior (at intermediate fear levels) or minimal exploratory behavior (at very high fear levels). Nondefecating rats will show an intermediate level of activity.Lester also reported the existence of a sex difference in the exploratory behavior of rats. For male rats food deprivation increased exploratory behavior whereas for female rats deprivation decreased exploratory behavior. Lester advanced an explanation of this phenomenon that was predicated upon male rats having a lower basal fear level than female rats. Increasing deprivation was assumed to increase the fear level of the animals (Mowrer, 1960), and this has different effects on male and female rats since their basal fear levels differ. A crucial test of this explanation would be to investigate the fear levels of satiated male and female rats.The present experiment was designed (a) to see whether a U-shaped function obtains between exploratory activity and defecation, and (b) to see whether satiated female rats defecate more than satiated male rats, in an open-field test of exploration. MethodThe Ss were 30 male and 30 female rats from the Charles River Breeding Laboratories, strain CD. They arrived in the laboratory aged 60 days. They were housed Singly with ad lib food and water.

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Section: Discussionsupporting

confidence: 87%

Section: It Was Predicted From a Fear-motivated Theory Of Explorationmentioning

confidence: 99%

Two tests of a fear-motivated theory of exploration

Lester

1968

Psychon Sci

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“…This supports my criticism (Lester, 1967b(Lester, , 1968 of the use of locomotion as a measure of exploration. Such a measure fails to identify within maze unit exploration and identifies only between maze unit exploration.…”

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confidence: 71%

“…Both mazes present a three-dimensional array of stimuli. The precise nature of this array is not of crucial significance for my general theory (Lester, 1967b(Lester, , 1968.…”

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confidence: 99%

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Lester

1968

Psychon Sci

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“…They also showed a lower level of alternation between arms at the first opportunity: that is to say, having been placed in one arm (A), and having entered a second arm (B), they were less likely than rats in the enclosed maze to make their next entry into the third arm (C). Lester takes these results as supporting a theory of exploratory behavior (Lester, 1967b) according to which the probability of a rat's approaching a stimulus in its environment fIrst increases and then decreases as a function of the fear aroused by that stimulus. The fear aroused by a stimulus is held to depend partly on its novelty, and partly on the rat's basal level of fear.…”

mentioning

confidence: 76%

Exploratory behavior: The inadequacy of activity measures

Sheldon

1968

Psychon Sci

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It has been reported that rats show lower activity and alternation scores in an elevated maze than they do in an enclosed maze, -and it has been argued that this can be explained by a theory relating exploration to anxiety. But it is shown here that behavior in the two kinds of maze is so different that these comparisons do not justify the conclusions drawn from them. Lester (1967a) has compared the locomotor activity of rats in an elevated and an enclosed Y maze of similar dimensions and reported two differences. Rats in the elevated maze moved less often from one maze arm to another. They also showed a lower level of alternation between arms at the first opportunity: that is to say, having been placed in one arm (A), and having entered a second arm (B), they were less likely than rats in the enclosed maze to make their next entry into the third arm (C). Lester takes these results as supporting a theory of exploratory behavior (Lester, 1967b) according to which the probability of a rat's approaching a stimulus in its environment fIrst increases and then decreases as a function of the fear aroused by that stimulus. The fear aroused by a stimulus is held to depend partly on its novelty, and partly on the rat's basal level of fear.If this theory is to explain Lester's results, a number of assumptions have to be made. It must be assumed that rats in an elevated maze are generally more fearful than rats in an enclosed maze. Lester provides no independent evidence for this, but Halliday (1967) has recently reported that rats defecated more in an elevated maze. It must also be assumed that the measure Lester took of locomotor activity (the number of occasions on which a rat moved from one maze arm to another) is a measure of the rat's exploratory approaches to the stimuli in its environment, and further that it is an equally appropriate measure in both kinds of maze. But before we are justifIed in making this last assumption (and concluding, as Lester's theory predicts, that rats in elevated mazes explore less) we need to examine the behavior more carefully. An elevated and an enclosed maze may have identical ground plans, but they necessarily present the rat with very different sensory environments. In particular, of course, extramaze cues are likely to be far more prominent with an elevated maze. It may be, therefore, that there will be gross differences in behavior in the two situations, and that different patterns of response may have a claim to be called exploratory. If this proved to be so, comparisons based simply on Lester's measure of locomotor activity would obviously be unsatisfactory. 38The following results (extracted from a longer experiment with rats in an elevated maze) seem to be relevant.Method. The Ss were 18 hooded female rats, without previous maze experience, and about 100 days old. Each rat was observed for 3 min on each of three successive days in a wooden elevated Y maze. The arms, measuring 18 x 4 in. were set at angles of 120 deg to each other. The maze was supported 18 in. above the floor w...

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Sex Differences in Exploration: Toward a Theory of Exploration

Cited by 40 publications

References 27 publications

Two tests of a fear-motivated theory of exploration

Two tests of a fear-motivated theory of exploration

Reply to Sheldon

Exploratory behavior: The inadequacy of activity measures

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