Perception of the Ponzo illusion by rhesus monkeys, chimpanzees, and humans: Similarity and difference in the three primate species

Abstract

In Experiment 1, 3 rhesus monkeys and 1 chimpanzee were tested for their susceptibility to the Ponzo illusion. The subjects were first trained to report the length of the target bar presented at the center of the computer display by touching either of the two choice locations designated as "long"or "short." When inverted-V context lines were superimposed on the target bar, the subjects tended to report "long" more often as the apex of these upward-converging lines approached the target bar. The perception of the Ponzo illusion was thus demonstrated. In Experiment 2, the same 3 rhesus monkeys and 2 new chimpanzees were tested using two types of context lines that provided different strengths of linear perspective. The subjects showed a bias similar to that found in Experiment 1,but there was no difference in the magnitude of the bias between the two types of context in either species. This failed to support the classic account for the Ponzo illusion, the perspective theory, raised by Gregory (1963). In Experiment 3, the magnitude of the illusion was compared between the inverted-V context and the context consisting of short vertical lines having the same gap as the former in the same 3 rhesus monkeys and 2 of the chimpanzees from the preceding experiments. While the chimpanzees showed the illusion for both types of stimuli, the monkeys showed no illusion for the latter. In Experiment 4, 6 humans were tested in a comparable procedure. As in the nonhuman primates, the illusion was unaffected by the strength of linear perspective. On the other hand, the humans showed considerably larger illusion for the context consisting of vertical lines than for contexts consisting of converging lines. Thus, there was a great species difference in the effect of the gap itself on the magnitude of the Ponzo illusion. Similarity found at first turned out to be no more than superficial. Possible sources of this species difference are discussed.Nonhuman primates are commonly used as a model in the study of human information processing, especially in neuroscience. The rationale of this lies in that they are the species closest to humans and at the least their fundamental perceptual processes ought to be similar to those of humans.Actually, for example, perception of some natural and geometric patterns has been shown to be similar not only among primates but also among species from different taxa

Perceptual completion in rhesus monkeys (Macaca mulatta) and pigeons (Columba livia)

“…Since both subjects had learned a similar task before the start of this experiment (Fujita, 1996(Fujita, , 1997, they started on the baseline discrimination with the isolated target bar (i.e., without the gray box). Sessions consisted of 192 trials.…”

Why do animals differ in their susceptibility to geometrical illusions?

“…In accordance with this proposal, we compiled findings from non-human animal species across six geometrical illusions within three different environmental contexts (aquatic, terrestrial, aerial). To the best of our knowledge, at the present time, research on susceptibility to geometrical illusions in nonhuman animals has been restricted to the following species: homing pigeons, ringneck doves, bantam chickens, Fujita (1996) 2 Macaca mulatta (rhesus monkeys); 8-year-old male, 7-year-old female Size-classification task Yes Timney and Keil (1996) 2 Equus caballus (horses); both female, aged 7 and 15 years Two-choice discrimination task Yes Fujita (1997) 3 Macaca mulatta (rhesus monkeys); 1 male, 2 females aged 5 and 6 years Size-classification task Yes 1 Pan troglodytes (chimpanzee); female aged 18 years Barbet and Fagot (2002) African gray parrots, baboons, capuchin monkeys, rhesus monkeys, chimpanzees, redtail splitfin fish, bamboo sharks, horses, rats, and bottlenose dolphins (Fig. 1).…”

Do Dogs Demonstrate Susceptibility to a Vertically Presented Ponzo Illusion?

“…If it is correct that dogs are not susceptible to the Ponzo illusion, this has implications for underlying theoretical explanations for illusion susceptibility, as five terrestrial species, ranging from rats to chimpanzees, have all demonstrated susceptibility (Barbet & Fagot, 2002;Bayne & Davis, 1983;Fujita, 1997;Fujita et al, 1991;Imura et al, 2008;Nakagawa, 2002;Timney & Keil, 1996). It is possible that dogs differ from these other species in terms of their perceptual cognitive style, preferring to focus on local cues (individual components of a stimulus) rather than global cues (viewing the stimulus as a whole).…”

“…Some species demonstrate human-like susceptibility, some demonstrate no susceptibility, and some demonstrate reversed susceptibility (e.g., Agrillo, Parrish, & Beran, 2014;Fujita, 1996Fujita, , 1997Murayama, Usui, Takeda, Kato, & Maejima, 2012;Nakamura, Watanabe, & Fujita, 2008;Sovrano, Albertazzi, & Salva, 2014;Watanabe, Nakamura, & Fujita, 2011. Moreover, even within a species, mixed findings have been observed in susceptibility to the same illusion (e.g., Nakamura et al, 2008Nakamura et al, , 2014Salva, Rugani, Cavazzana, Regolin, & Vallortigara, 2013).…”

“…Across these tests assessing susceptibility to the Ponzo illusion, our evidence converged on the conclusion that, as a group, dogs are not susceptible to the illusion. These findings are of particular interest as, to date, some individual pigeons (Fujita, Blough, & Blough, 1991), Sprague-Dawley rats (Nakagawa, 2002), horses (Timney & Keil, 1996), rhesus macaques (Bayne & Davis, 1983;Fujita, 1997), baboons (Barbet & Fagot, 2002), and chimpanzees (Fujita, 1997;Imura, Tomonaga, & Yagi, 2008), have all demonstrated human-like susceptibility to the Ponzo illusion. Figure 1.…”