New Caledonian crows plan for specific future tool use.

The ability to plan for future events is one of the defining features of human intelligence. Whether non-human animals can plan for specific future situations remains contentious: despite a sustained research effort over the last two decades, there is still no consensus on this question. Here, we show that New Caledonian crows can use tools to plan for specific future events. Crows learned a temporal sequence where they were (a) shown a baited apparatus, (b) 5 min later given a choice of five objects and (c) 10 min later given access to the apparatus. At test, these crows were presented with one of two tool-apparatus combinations. For each combination, the crows chose the right tool for the right future task, while ignoring previously useful tools and a low-value food item. This study establishes that planning for specific future tool use can evolve via convergent evolution, given that corvids and humans shared a common ancestor over 300 million years ago, and offers a route to mapping the planning capacities of animals.

Orangutans (Pongo pygmaeus and Pongo abelii) understand connectivity in the skewered grape tool task.

Great apes appear to have limited knowledge of tool functionality when they are presented with tasks that involve a physical connection between a tool and a reward. For instance, they fail to understand that pulling a rope with a reward tied to its end is more beneficial than pulling a rope that only touches a reward. Apes show more success when both ropes have rewards tied to their ends but one rope is nonfunctional because it is clearly separated into aligned sections. It is unclear, however, whether this success is based on perceptual features unrelated to connectivity, such as perceiving the tool's separate sections as independent tools rather than one discontinuous tool. Surprisingly, there appears to be no study that has tested any type of connectivity problem using natural tools made from branches with which wild and captive apes often have extensive experience. It is possible that such ecologically valid tools may better help subjects understand connectivity that involves physical attachment. In this study, we tested orangutans with natural tools and a range of connectivity problems that involved the physical attachment of a reward on continuous and broken tools. We found that the orangutans understood tool connectivity involving physical attachment that apes from other studies failed when tested with similar tasks using artificial as opposed to natural tools. We found no evidence that the orangutans' success in broken tool conditions was based on perceptual features unrelated to connectivity. Our results suggest that artificial tools may limit apes' knowledge of connectivity involving physical attachment, whereas ecologically valid tools may have the opposite effect.

Mental evolution and development: evidence for secondary representation in children, great ages, and other animals.

Recent interest in the development and evolution of theory of mind has provided a wealth of information about representational skills in both children and animals. According to J. Perner (1991), children begin to entertain secondary representations in the 2nd year of life. This advance manifests in their passing hidden displacement tasks, engaging in pretense and means-ends reasoning, interpreting external representations, displaying mirror self-recognition and empathic behavior, and showing an early understanding of "mind" and imitation. New data show a cluster of mental accomplishments in great apes that is very similar to that observed in 2-year-old humans. It is suggested that it is most parsimonious to assume that this cognitive profile is of homologous origin and that great apes possess secondary representational capacity. Evidence from animals other than apes is scant. This analysis leads to a number of predictions for future research.

Imitation, mirror neurons and autism.

Various deficits in the cognitive functioning of people with autism have been documented in recent years but these provide only partial explanations for the condition. We focus instead on an imitative disturbance involving difficulties both in copying actions and in inhibiting more stereotyped mimicking, such as echolalia. A candidate for the neural basis of this disturbance may be found in a recently discovered class of neurons in frontal cortex, 'mirror neurons' (MNs). These neurons show activity in relation both to specific actions performed by self and matching actions performed by others, providing a potential bridge between minds. MN systems exist in primates without imitative and 'theory of mind' abilities and we suggest that in order for them to have become utilized to perform social cognitive functions, sophisticated cortical neuronal systems have evolved in which MNs function as key elements. Early developmental failures of MN systems are likely to result in a consequent cascade of developmental impairments characterised by the clinical syndrome of autism.

An evaluation of a suburban railway pedestrian crossing safety programme.

This study evaluated a programme of educational and environmental (access prevention) interventions designed to reduce the incidence of illegal and unsafe crossing of the rail corridor at a suburban station in Auckland, New Zealand. Immediately after the programme of interventions, the proportion of those crossing the rail corridor by walking across the tracks directly rather than using the nearby overbridge had decreased substantially. Three months later, the decrease was even greater. However, the educational and environmental interventions were introduced simultaneously so that the effects of each could not be separated; nor could other unmeasured factors be ruled out. Anonymous surveys administered immediately before and 3 months after the interventions indicated that while awareness of the illegality of walking across the tracks had increased slightly, perception of risk had not changed. This suggests that the educational interventions may have had less effect than the access prevention measures.

Children's understanding of the relation between delayed video representation and current reality: a test for self-awareness?

This study investigated whether children's ability to recognize themselves in delayed video feedback indicates changes in self-awareness (Povinelli, Landau, & Perilloux, 1996, Child Development, 67, 1540-1554). Children were presented with 3-min-old videos of themselves to test whether they would investigate the current state of affairs upon seeing a surprising element in the video. In one condition, a sticker had been covertly placed into the child's hair, and in another an object had been hidden in a box. Both conditions proved equally difficult and performance correlated. Four-year-olds performed better than 3-year-olds, and children who failed the tasks retrieved the "surprise" item when presented with a mirror. There was no evidence to suggest that children's difficulties were due to immature metarepresentational thinking, lack of experience, problems with the questions, or problems appreciating the correspondence between image and referent. Yet, the parallel results in both conditions and the likelihood of false positives and false negatives indicate that the video test in its present form may not be a valid measure of differences in self-awareness.

Mental time travel and the evolution of the human mind.

This article contains the argument that the human ability to travel mentally in time constitutes a discontinuity between ourselves and other animals. Mental time travel comprises the mental reconstruction of personal events from the past (episodic memory) and the mental construction of possible events in the future. It is not an isolated module, but depends on the sophistication of other cognitive capacities, including self-awareness, meta-representation, mental attribution, understanding the perception-knowledge relationship, and the ability to dissociate imagined mental states from one's present mental state. These capacities are also important aspects of so-called theory of mind, and they appear to mature in children at around age 4. Furthermore, mental time travel is generative, involving the combination and recombination of familiar elements, and in this respect may have been a precursor to language. Current evidence, although indirect or based on anecdote rather than on systematic study, suggests that nonhuman animals, including the great apes, are confined to a "present" that is limited by their current drive states. In contrast, mental time travel by humans is relatively unconstrained and allows a more rapid and flexible adaptation to complex, changing environments than is afforded by instincts or conventional learning. Past and future events loom large in much of human thinking, giving rise to cultural, religious, and scientific concepts about origins, destiny, and time itself.