Results that point to animals' metacognitive capacity bear a heavy burden, given the potential for competing behavioral descriptions. In this article, formal models are used to evaluate the force of these descriptions. One example is that many existing studies have directly rewarded so-called uncertainty responses. Modeling confirms that this practice is an interpretative danger because it supports associative processes and encourages simpler interpretations. Another example is that existing studies raise the concern that animals avoid difficult stimuli not because of uncertainty monitored, but because of aversion given error-causing or reinforcement-lean stimuli. Modeling also justifies this concern and shows that this problem is not addressed by the common practice of comparing performance on chosen and forced trials. The models and related discussion have utility for metacognition researchers and theorists broadly, because they specify the experimental operations that will best indicate a metacognitive capacity in humans or animals by eliminating alternative behavioral accounts.
Humans feel uncertain when they do not know or remember. They often respond appropriately to these feelings. These responses are the empirical phenomena that ground the literature on metacognition (Flavell, 1979;Koriat, 1993; Nelson, 1992; Schwarte, 1994). The idea in this literature is that a cognitive executive in the mind monitors perception and memory, judging its progress and prospects. This happens, for example, when we realize the difficulty of a passage in a scientific article and make deliberate efforts to grasp its meaning. These monitoring functions are assessed in the laboratory by collecting metacognitive judgments (e.g., feelings of knowing or confidence ratings).
Researchers take humans' metacognitive behavior to indicate important aspects of mind. They link metacognitive states to self-awareness (because uncertainty and doubt are so personal and subjective; Gallup, 1982) and to declarative consciousness (because humans so easily introspect and communicate these states; Koriat, 2007; Nelson, 1996). Metacognition is one of humans' sophisticated cognitive capacities, and it could be uniquely human (Metcalfe & Kober, 2005). This possibility makes it important to ask whether nonhuman animals (hereafter, animals) have a similar capacity.
Accordingly, Smith and his colleagues inaugurated a new area of comparative inquiry by asking whether animals have a capacity for cognitive monitoring (Shields, Smith, & Washburn, 1997; Smith et al., 1995; Smith, Shields, Allendoerfer, & Washburn, 1998; Smith, Shields, Schull, & Washburn, 1997). Active research continues in this area (Beran, Smith, Redford, & Washburn, 2006; Call & Carpenter, 2001 ; Foote & Crystal, 2007; Hampton, 2001; Inman & Shettleworth, 1999; Kornell, Son, & Terrace, 2007; Washburn, Smith, & Shields, 2006; see reviews in Smith, in press; Smith, Shields, & Washburn, 2003; Smith & Washburn, 2005). In some of these studies, researchers presented a mix of easy and difficult trials. They gave animals (a dolphin, monkeys, pigeons, and rats) an additional response-beyond the primary discrimination responses-that let them decline to complete any trials they chose. Animals who accurately monitor cognition should recognize difficult trials as error risking and decline those trials selectively. Some animals do so and, in cognitive-monitoring tasks, produce data patterns like those of humans. This additional response has come to be called the uncertainty response, and it is presently interpreted as showing some species' capacity for uncertainty monitoring and metacognition.
If this interpretation is correct, these experiments tap theoretically important cognitive capacities in animals. They raise intriguing issues about animal mind, awareness, and consciousness, although they do not resolve them. They could help cognitive scientists reflect on the phylogenetic roots of human metacognition. …