An Analysis of Behavior Directed toward Foreign Marks on the Body in Rhesus Macaques ( Macaca mulatta): Salience and Motivation Underlie Response Open Access

Roberts, Rebecca Ann (2011)

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Self-awareness is essential for social cognition and there is a continuing debate over
which primates possess self-awareness. The most common view is that self-awareness
only exists in humans and apes, all other primates do not appear to be self-aware. This
conclusion is based primarily upon the results from the mark test, a test of mirror self-
recognition developed by Gordon Gallup (1970). However, passing the mark test
requires both understanding the contingencies of mirrors and a motivation to inspect
foreign marks on the body. If either of these requirements is not met, then failing the
mark test does not demonstrate an absence of mirror self-recognition or self-awareness.
In order to assess how motivated rhesus monkeys are to inspect marks, we analyzed self-
directed behavior of twelve juvenile rhesus macaques towards five different foreign
marks placed in plain view on their bodies: touch area, shaved area, finger paint, peanut
butter, and sticker. These marks varied in salience and it was predicted that high salience
marks, such as peanut butter would be attended to compared to low salience marks such
as a shave mark. Mark-directed behaviors were significantly influenced by the type of
mark. Finger paint, a mark similar to the marks typically used in the mark test, was not
touched more frequently than chance and did not differ significantly from touch-only and
shave marks. Peanut butter elicited significantly more self-directed behaviors than
expected by chance and than any other mark. These results suggest that not only does the
salience of a mark influences the frequency and duration of self-investigative behaviors
of a foreign mark placed on the body, but also that the types of marks generally used
when testing for mirror self-recognition may not be salient enough to elicit self-
investigative behaviors in rhesus monkeys. Species differences that have been observed
in performances on the mark test may be attributed to species differences in motivation to
inspect marks on their bodies and not to a qualitative difference in mirror self-recognition
or self-awareness.

Table of Contents

Table of Contents

Introduction...1 Methods...9 Subjects...9 Apparatus and Procedures...9 Analysis...11 Results...13

Comparison of Other-Directed Behavior in Trials One and Two...13

Comparison of Unmarked-Target-Directed Behavior and...13

Other-Directed Behavior

Comparison of Marked-Target-Directed Behavior and...14

Other-Directed Behavior (Trial Two)

Comparison of Marked-Target-Directed Behavior and...15

Unmarked-Target-Directed Behavior Between-Subject Factors: Sex and Age...17

Individual Differences in Marked-Target-Directed Behavior...18

Discussion...18 References...27 Tables...30 Figure Captions...31 Figures...33

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