Picture recognition in animals and humans

Review article

Picture recognition in animals and humans

Dalila Bovet ^a, Jacques Vauclair ^a,b,*

^a Centre de recherche en Neurosciences Cogniti6es, CNRS -CRNC, 31, chemin Joseph -Aiguier, 13402 Marseille Cedex 20, France
^b Department of Psychology, Uni 6 ersite de Pro 6 ence, 29, a 6. Robert Schuman, 13621 Aux - en - Pro 6 ence Cedex 1, France

Received 4 June 1999; received in revised form 27 December 1999; accepted 27 December 1999

Abstract

The question of object - picture recognition has received relatively little attention in both human and comparative psychology;
a paradoxical situation given the important use of image technology (e.g. slides, digitised pictures) made by neuroscientists in their
experimental investigation of visual cognition. The present review examines the relevant literature pertaining to the question of the
correspondence between and/or equivalence of real objects and their pictorial representations in animals and humans. Two classes
of reactions towards pictures will be considered in turn: acquired responses in picture recognition experiments and spontaneous
responses to pictures of biologically relevant objects (e.g. prey or conspecifics). Our survey will lead to the conclusion that humans
show evidence of picture recognition from an early age; this recognition is, however, facilitated by prior exposure to pictures. This
same exposure or training effect appears also to be necessary in nonhuman primates as well as in other mammals and in birds.
Other factors are also identified as playing a role in the acquired responses to pictures: familiarity with and nature of the stimulus
objects, presence of motion in the image, etc. Spontaneous and adapted reactions to pictures are a wide phenomenon present in
different phyla including invertebrates but in most instances, this phenomenon is more likely to express confusion between objects
and pictures than discrimination and active correspondence between the two. Finally, given the nature of a picture (e.g.
bi-dimensionality, reduction of cues related to depth), it is suggested that object - picture recognition be envisioned in various
levels, with true equivalence being a limited case, rarely observed in the behaviour of animals and even humans. © 2000 Elsevier
Science B.V. All rights reserved.

Keywords: Behaviour; Electrophysiology; Spontaneous responses; Acquired responses; Invertebrates; Birds; Mammals; Humans

1. Introduction

Researchers in animal and in human cognition fre-
quently use photographs or slides in place of real
objects in their studies of categorisation, face recogni-
tion, etc., but paradoxically, there are few experiments
either with animals or humans that have explicitly
addressed the question of the equivalence between an
object and its picture. In other words, it is not obvious
that animal and human subjects do really interpret the
2-D stimuli as the 3-D objects they represent. For
example, the success obtained in training pigeons
[40,63] or monkeys [13,80,112] to categorise photo-
graphic slides does not prove that the animals under-

* Corresponding author.

E -mail address: [email protected] (J. Vauclair)
stand what the pictures they categorise actually
represent. In fact, as we will see in this paper, some
studies have demonstrated that this is not the case,
while others have shown that the establishment of some
equivalence between the real object and its pictorial
representation is dependent upon both the stimulus’
dimensions and experimental and/or motivational con-
ditions. The present review tries to take stock of this
question by examining the available literature for hu-
mans (mostly infants) and nonhuman subjects.

This review will first examine experiments concerning
humans and will subsequently consider studies with
nonhuman subjects, with the latter being classified into
three categories. The first category comprises of cases
of convincing demonstrations in which animals are able
to treat pictures like the stimuli they represent; we can
assume that a picture is recognised when animals react

0166-4328/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S0166-4328(00)00146-7

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