Reversibility of Ambiguous Figures for Informed and Uninformed Subjects

Kate Lowry and Susanne Cook

00kjlowr@alma.edu and 01smcook@alma.edu

Previous research has found that the reversibility of ambiguous figures, or pictures that can be perceived in more ways than one, is unlikely for subjects who are unaware that the figure is ambiguous; in addition, reversals occur under certain conditions in which the subject is informed of the ambiguous figures possible alternatives (Girgus et al 1977; Rock & Mitchener 1992).
Some experiments have explored the effect of age on the reversibility of ambiguous figures. Beer et al tested a population of university students, young adults, and elderly people and found that more reversals occurred for the university students than the other age groups (1989). Rock et al investigated the reversibility of ambiguous figures for three-year olds and four-year olds (1994). They found that none of the children reversed the ambiguous figures in the uninformed condition; more surprisingly, Rock et al found that young children in the informed condition had the tendency to not reverse the ambiguous figures. This study was modeled after the experiment conducted by Girgus et al in 1977. It was hypothesized that subjects in the uninformed condition will be less likely to report reversals of the ambiguous figures than those subjects in the informed condition.

Method
Subjects: Forty full time Alma College students were divided into two equal groups--the uninformed and informed groups.

Materials: Seven figures were viewed by each subject. The following four were reversible figures: 1. Sara Nader - a man serenading a bird with a saxophone a woman's face; 2. Eskimo/Indian; 3. Mother/Daughter/Father; 4. Father/Son (see Figure 1). The other three figures were controls.

Figure 1: The Four Reversible Figures Used in the Experiment. Sara Nader--upper left hand corner (Shepard 1990); Eskimo/Indian--upper right hand corner, Mother/Father/Daughter--lower left hand corner, Father/Son--lower right hand corner (Internet Source 1999).

Procedure: Each subject was assured that the test was not an intelligence test. Subjects were instructed to keep their eyes on the figures at all times, and every ten seconds the experimenter tapped a pen on a desk after which the subject was to report what figure he/she saw. The figures were shuffled before viewing by each subject so as to obtain randomness. Subjects viewed each figure for one minute. Subjects in the informed group received further instruction before viewing the cards. They were told of the possibility of reversible figures and were shown the rat/man figure. Uninformed subjects were informed of the possibility of reversible figures and were shown the rat/man figure after having viewed all seven figures. At the conclusion of testing each subject was asked the following questions: 1. Have you ever taken Sensation & Perception or any other class that has covered the reversibility of ambiguous figures? 2. In general, have you ever been exposed to ambiguous figures? If so, which ones? (i.e.. old woman/young woman is very popular).
Results
The mean reversal time of each ambiguous figure was calculated for the subjects who reported reversal (see Table 1).

In viewing the Sara Nader figure, the uninformed group had a mean reversal time of 22.2 seconds while the informed group had a mean reversal time of 18.9 seconds. The Eskimo/Indian ambiguous figure was resulted in a mean reversal time of 25 seconds for the uninformed subjects and a mean reversal time of 19.3 seconds for the informed participants. The Mother/Father/Daughter ambiguous figure resulted in a first reversal mean time of 14.3 seconds for the uninformed participants and a first reversal mean time of 20.6 seconds for the informed subjects (see Figure 2).

Figure 2. Mean Reversal Times for Uninformed and Informed Subjects. Please note that subjects who reported no reversal were not included in the calculation of the mean reversal times. In addition, because the Father/Son and the second reversal of the Mother/Father/Daughter had fewer than 10 subjects reporting reversal, comparison of the means is not a reasonable analysis of data.

Discussion
    One would expect to find a shorter reversal time for the informed subjects as opposed to the uninformed subjects. This was shown to be true in all cases, except for the first reversal of the Mother/Father/Daughter figure. Subjects in the informed group had a mean reversal latency of 20.6 seconds while subjects in the uninformed group had a mean reversal latency of 14.3 seconds. Earlier reversal for the uniformed subjects could be attributed to the fact that there was more opportunity for reversal. It was also hypothesized that subjects in the uninformed group would be less likely to report reversals of the ambiguous figures. This hypothesis, for the most part, was supported by the collected data. However, more subjects reported reversal of the Father/Son figure in the uninformed group (10) than in the informed group (3). In addition, more subjects reported both reversals of the Mother/Father/Daughter figure in the uninformed group (11) than did subjects in the informed group (7).
    Lack of support for the proposed hypothesis could be due to the fact that the college population is not naive to the idea of ambiguous figures. Of the 40 subjects tested 14 reported having taken a class that covered the reversibility of ambiguous figures. Thirty-one of the 40 participants had previous encounters with ambiguous figures and were able to recall such figures as the old woman/young woman, the vase/2 faces, Father/Son, rat/man, rabbit/duck, two lovers with vines/Dionysus, and the Necker Cube. One must also consider the degree of difficulty in reversal for each ambiguous figure. Some figures were obviously easier to reverse than others. For example, the Sara Nader was reversed by 18 subjects in both the uninformed and the informed groups whereas the Father/Son figure was reversed by only 3 participants in the informed group and 10 in the uninformed group.
    Future research on the reversibility of ambiguous figures for uninformed and informed participants should target middle-schoolers or elementary school students. New ambiguous figures should be developed for testing so as to avoid the possibility of subjects having already viewed particular ambiguous figures.

References
Beer, J., Beer, J., Markley, R. P., & Camp, C. J. Age and living conditions as related to perceptions of ambiguous figures. Psychological Reports, 1989, 64, 1027-1033.

Girgus, J. J., Rock, I., & Egatz, R. The effect of knowledge of reversibility on the reversibility of ambiguous figures. Perception & Psychophysics, 1977, 22 (6), 550-556.
Internet Source. April 1999. Http://www.sandlotscience.com/ Ambiguous/Ambiguous.frm.htm.

Rock, I., Gopnik, A., & Hall, S. Do young children reverse ambiguous figures? Perception, 1994, 23, 635-644.

Rock, I., & Mitchener, K. Further evidence of failure of reversal of ambiguous figures by uninformed subjects. Perception, 1992, 21, 39-45.

Shepard, Roger N. Mindsights. New York: W. H. Freedman & Company, 1990, pg. 76.