Dogs have an unusual ability for reading human communicative gestures (e.g., pointing) in comparison to either nonhuman primates (including chimpanzees) or wolves [1, 2, 3, 4, 5, 6, 7 and 8]. Although this unusual communicative ability seems to have evolved during domestication [6 and 8], it is unclear whether this evolution occurred as a result of direct selection for this ability, as previously hypothesized [8], or as a correlated by-product of selection against fear and aggression toward humans [9]?as is the case with a number of morphological and physiological changes associated with domestication [11, 12, 13, 14, 15, 16, 17 and 18]. We show here that fox kits from an experimental population selectively bred over 45 years to approach humans fearlessly and nonaggressively (i.e., experimentally domesticated) are not only as skillful as dog puppies in using human gestures but are also more skilled than fox kits from a second, control population not bred for tame behavior (critically, neither population of foxes was ever bred or tested for their ability to use human gestures) [11 and 12]. These results suggest that sociocognitive evolution has occurred in the experimental foxes, and possibly domestic dogs, as a correlated by-product of selection on systems mediating fear and aggression, and it is likely the observed social cognitive evolution did not require direct selection for improved social cognitive ability.

How do we develop self-awareness, or a sense of self? One of the most popular theories is that language plays a major role: language and the narrative form allow us to develop a sense of self because this sense is dependent upon representational thought and the psychological manipulation of representations. Some scholars argue against this theory, claiming that more than language and representational thought is needed. Comparing human and animal cognition is a particularly powerful way of examining this disagreement; if animals possess self-awareness without having the representational linguistic capabilities of humans, then the comparison will provide significant evidence for the argument that language and narrative form do not play the only role, and that researchers may have overlooked a cognitive link. Terrace and Metcalfe propose to facilitate this work of some participants, such as Endel Tulving, Janet Metcalfe, and Daniel Povinelli, shows that self-awareness, metacognitions, and representational thought are unique to humans, while that of precursors to self-aware thought processes exist in non-human primates, the debate is likely to be lively and informative. This volume will be of great interest to researchers in cognitive, developmental, and social psychology.

The relationship between age, relative numerousness judgment, and summation was investigated in 11 Western lowland gorillas (Gorilla gorilla gorilla). Experiments 1 and 2 evaluated the gorillas? ability to select the larger of 2 food quantities before and with training. The majority of gorillas did not reliably select the larger quantity in Experiment 1 until receiving training to do so in Experiment 2. Experiment 3 evaluated their ability to select the larger of 2 pairs of quantities. All gorillas selected the larger pair more often than chance, and the old were less accurate and slower than were the young. For most gorillas, performance in relative numerousness judgment with training and summation was comparable with previous reports in chimpanzees and orangutans.

A recent article by Onishi and Baillargeon presents evidence that 15-month-old infants attribute false beliefs (FBs) to other people. If correct, it lends dramatic new support to the idea that mental state concepts (?theory of mind?) emerge from a specialized neurocognitive mechanism that matures during the second year of life. But it also raises new puzzles concerning the FB task - puzzles that have intriguing parallels in results from infants? reasoning about solid bodies.

This book brings together research, from different disciplines, to examine contemporary tool use in various domains, presenting a single coherent account of human tool use.

Animals from numerous taxa use auditory information to functionally deceive other individuals, either by producing or withholding various vocal signals. However, little empirical evidence has demonstrated that any nonhuman species recognizes how manipulating auditory information can alter the knowledge state of other individuals. We explored whether one monkey species, the rhesus macaque, understands the connection between hearing and knowing. Monkeys were presented with the opportunity to take grapes from a human competitor who was looking away. One of two grapes was placed inside a silent container, and the other was placed inside a noisy container. We predicted that subjects would selectively choose the silent container over the noisy container, because the noisy container might alert the human competitor to the subject?s actions. As predicted, subjects reliably took the grape from inside the silent container when the competitor was not looking. In contrast, subjects chose randomly when the competitor was looking and therefore already knew about the subject?s approach. These results demonstrate that monkeys preferentially attempted to obtain food silently only in conditions in which silence was relevant to obtaining food undetected.

Self-control is defined as forgoing immediate gratification to obtain a greater reward. Tool use may relate to self-control because both behaviors may require foresight and deliberate control over one?s actions. The authors assessed 20 capuchin monkeys (Cebus apella) for the ability to delay gratification in a tool task. Subjects were given rod-shaped food items that could either be consumed immediately or be carried to an apparatus and used to extract a more preferred food. The authors found that some monkeys were able to exhibit self-control. Monkeys with relatively more tool use experience demonstrated the greatest levels of self-control. These results indicate that capuchins are capable of delaying gratification when a higher quality reinforcer is present and that tool experience can influence levels of self-control in this task.