Children's understanding of ambiguous figures: Which cognitive developments are necessary to experience reversal?

Abstract

In two experiments involving one hundred and thirty-eight 3- to 5-year-olds we examined the claim that a complex understanding of ambiguity is required to experience reversal of ambiguous stimuli [Gopnik, A., & Rosati, A. (2001). Duck or rabbit? Reversing ambiguous figures and understanding ambiguous representations. Developmental Science, 4, 175–183]. In Experiment 1 a novel Production task measured the ability to acknowledge both interpretations of ambiguous figures. This was as easy as and significantly correlated with a False Belief task, and easier than a Droodle task. We replicated this finding in Experiment 2, and also found that perceiving reversal of ambiguous figures was harder than either the False Belief or Production tasks. In contrast to previous findings, the Reversal and Droodle tasks were not specifically related. We conclude that children only attempt reversal once they can understand the representational relationship between the figure and its two interpretations. The process resulting in reversal however is hard, probably requiring additional developments in executive functioning and imagery abilities.

Introduction

This paper investigates at what age children are able to reverse ambiguous figures, and what conceptual abilities are necessary for this ability. Ambiguous figures are pictures, which have two different interpretations such as the duck–rabbit (Jastrow, 1900), man–mouse (Bugelski & Alampay, 1961), and vase-faces (Rubin, 2000) (see Fig. 1). When informed adults view these figures they tend to experience them reversing from one interpretation to the other. Research by Rock and co-workers suggests that for this to happen, adults must know that the figure is ambiguous and what the interpretations are (Girgus, Rock, & Egatz, 1977; Rock & Mitchener, 1992; Rock, Hall, & Davis, 1994). This implies that reversal is a top-down active process. Perceivers must have a conceptual framework capable of representing that figures can have more than one interpretation, and the abilities necessary to bring about reversal.

However, some adults do experience reversals without being informed of the ambiguity. This might be because they have prior experience with ambiguous figures. Because young children are unlikely to have had such experience, Rock, Gopnik, and Hall (1994) (Gopnik & Rosati, 2001) examined spontaneous reversal in preschoolers. When uninformed of the ambiguity, and told to look at a figure for 60 s, no child ever reported reversal. These findings support the idea that in order to achieve reversal of an ambiguous figure, the viewer must be aware of the ambiguity.

There was also a developmental effect: even after the ambiguity had been clearly demonstrated to them, informed younger children were particularly unlikely to reverse. This suggests that either the necessary conceptual framework or the ability to bring about reversal arises during the preschool period. The aim of this paper is to examine these possibilities.

Gopnik and Rosati (2001) repeated the reversal procedure, adding a False Belief task (Experiment 1) and a ‘Droodle’ task (Experiment 2). The False Belief task tests for children's understanding of other people's beliefs, which contrast with the child's. It is generally accepted that success on the False Belief task demonstrates that children are able to represent the relationship between beliefs and the state of the world the beliefs are about. Understanding that an ambiguous figure can represent two distinct objects also requires children to be able to represent the representational relationship between the figure and the two interpretations. One therefore might expect an association between the two tasks. Gopnik and Rosati (2001) (Experiment 1) found no correlation between the tasks, and the Reversal task was considerably harder than the False Belief task.

The Droodle task requires children to report that a person only seeing a small unidentifiable portion of a stimulus will not know what it is (Taylor, 1988; Perner & Davies, 1991). The stimulus is ambiguous in the sense that it could plausibly be part of more than one picture. The task assesses children's understanding of the effect of this ambiguity on the mental state of the viewer. Typically children up until the age of 5 years wrongly judge that a viewer would know what the full picture was. Gopnik and Rosati (2001) found that performance on the Droodle task correlated very well with performance on the Reversal task (ϕ = 0.86, p < 0.0001) and performances hardly differed. Their tentative conclusion was that reversal requires an abstract and complex understanding of ambiguity. They did not provide any more detailed explanation of what this understanding of ambiguity might entail.

If correct, this finding would indicate that the critical development is in the conceptual prerequisites of reversal, rather than the ability to bring it about. It would also indicate what the conceptual prerequisites are: whatever gives rise to success on the Droodle task. However, this finding is surprising for several reasons. Both the Reversal and Droodle tasks require children to understand that a stimulus can have two interpretations, and is therefore, ambiguous. However, each has additional requirements that the other does not. The Droodle task also requires children to understand the effect of this ambiguity on the knowledge state of another person; the Reversal task does not. The Reversal task requires children to perform some kind of mental action; the Droodle task does not. Neither additional requirement seems trivial, so a strong association between the tasks would not be expected.

Because Gopnik and Rosati's (2001) findings were surprising, unexpected, and came from a small sample of only 28 participants, in pilot work for the present paper we compared performance on the Reversal, False Belief and Droodle tasks in a sample of sixty-two 3- to 5-year-olds (the methods of all three tasks were as used in the experiments reported below). We found that the Reversal and Droodle tasks were of similar difficulty, but were only very weakly related (r = .26, p < .05). The finding of a relatively weak relationship between the two tasks is consistent with our task analysis.

It therefore remains plausible that the conceptual prerequisites of reversal arise earlier than success on the Reversal or Droodle tasks. If reversal is a top–down process, children must first be able to understand that one figure can have two interpretations. This poses a representational puzzle similar to that posed by homonymy. Homonyms are words with two unrelated meanings, such as bat (sports equipment) and bat (flying animal). Both ambiguous figures and homonyms are tokens in a representational medium – pictorial or linguistic – which can represent different things depending on context. Understanding this requires children to represent the relationship between the representational medium and the situation referred to. False Belief and synonymy also require children to do this: synonymy, because one situation can be referred to by two different words, and False Belief because one situation can be represented by different beliefs (some of which may be false).

Children pass tasks assessing their understanding of homonymy, synonymy and False Belief at roughly the age of 4 years, and performances on these tasks have been found to be consistently intercorrelated (Doherty & Perner, 1998; Doherty, 2000; Perner, Stummer, Sprung, & Doherty, 2002). We would therefore expect children to pass a task requiring them to acknowledge the two interpretations of an ambiguous figure at the same age, and for their performance to correlate with performances on any of these other tasks.

Experiment 1 investigates whether children are able to acknowledge both interpretations of ambiguous stimuli at a younger age than they have been found to reverse. In order to do this we adapted the “say something different” (SSD) task, previously used to assess understanding of synonymy (e.g. Doherty & Perner, 1998; Perner et al., 2002) for use with ambiguous figures. Early ability to acknowledge both interpretations, and a continued lack of association between the Reversal and Droodle tasks would support the idea that the basic conceptual development involved is the ability to understand that one stimulus can have two interpretations. Possible additional cognitive developments, such as developments in executive function and imagery might also be involved; we consider these in Section 4.

In our novel SSD task the experimenter showed children an ambiguous figure and provided one interpretation, e.g. “rabbit”. The child's task was to name the alternative interpretation (“duck”). After some intervening trials, the experimenter showed the same figure, this time providing the other interpretation, e.g. “duck”. Again the child had to name the alternative interpretation (“rabbit”). Children were scored as successful on that item if they could supply the alternative interpretation on both occasions. This criterion was necessary since children would be successful half the time by providing their favored interpretation regardless of what the experimenter said.