 Gennaro (2004) takes a somewhat different tack. While allowing that animals lack the concept experience of green, he thinks that they might nevertheless possess the (simpler) concept seeing green. But here he faces a dilemma. There is, indeed, a simpler concept of seeing, grounded in the capacity to track eye-direction and line of sight. But this isn’t necessarily a higher-order concept. To say, in this sense, that someone sees green in just to say that there is some green in the line in which their eyes are pointed—no mental state needs to be attributed. In contrast, it appears that any concept of seeing that is genuinely higher-order will be one that it would be less plausible to attribute to most species of animal (given the comparative evidence). Perhaps a first-order explanation of experimental observations of animals is virtually always possible (see, for example, Carruthers 2008). But Gennaro (2012, chapter eight) ultimately argues that there is plenty of evidence that many animals are capable of metacognition (thinking about their own mental states) as well as mindreading (thinking about other minds).  For example, in the case of mindreading, rhesus monkeys seem to attribute visual and auditory perceptions to others in more competitive paradigms (Flombaum and Santos 2005) and crows and scrub jays return alone to caches seen by other animals and recache them in new places (Emery and Clayton 2001). Any evidence of deception or empathy in animals would also seem to indicate some kind of mindreading ability. In addition, many animals seem capable of metacognition (including possessing self-concepts) as evidenced by the presence of episodic memory, for example (Dere et al. 2006; see also the essays in Terrace and Metcalf 2005; Hurley and Nudds 2006).  A related debate takes place with respect to infant consciousness and the capacity of infants to have metacognitive and mindreading abilities (see Gennaro 2012, chapter seven, for some discussion).  