Suchergebnisse

Abstract We conducted four experiments with 56 adult dogs (Canis lupus familiaris) involving tasks where food was dropped through an opaque tube connected either vertically or diagonally to one of two or three goal boxes. In the first experiment, modelled after studies with children and primates, the dogs first searched significantly more often in the location directly beneath the drop‐off point (a gravity bias), although this box was not connected with the tube. These results are comparable to those of human infants and cotton‐top tamarins. Experiments 2–4 tested which problem solving strategy the dogs applied to find the food. Results show that they do not understand the physical mechanism of the tube itself, and they apply one of three search strategies: search the gravity box (the one below the drop‐off box); search the box in the middle; learn the correct location of the goal box. When the goal box was in the same location the dogs learned to search there over trials, that is, they learned to 'defy gravity', but when the location of the goal box changed over trials they showed no learning. These findings are compared with those from human infants and cotton‐top tamarins: like these species, the dogs can learn to overcome a gravity bias, but only when the reward is to be found in a consistent location.

AbstractThe present study examined whether 6‐ and 9‐month‐old Caucasian infants could categorize faces according to race. In Experiment 1, infants were familiarized with different female faces from a common ethnic background (i.e. either Caucasian or Asian) and then tested with female faces from a novel race category. Nine‐month‐olds were able to form discrete categories of Caucasian and Asian faces. However, 6‐month‐olds did not form discrete categories of faces based on race. In Experiment 2, a second group of 6‐ and 9‐month‐olds was tested to determine whether they could discriminate between different faces from the same race category. Results showed that both age groups could only discriminate between different faces from the own‐race category of Caucasian faces. The findings of the two experiments taken together suggest that 9‐month‐olds formed a category of Caucasian faces that are further differentiated at the individual level. In contrast, although they could form a category of Asian faces, they could not discriminate between such other‐race faces. This asymmetry in category formation at 9 months (i.e. categorization of own‐race faces vs. categorical perception of other‐race faces) suggests that differential experience with own‐ and other‐race faces plays an important role in infants' acquisition of face processing abilities.

Abstract Human infants, just a few days of age, are known to prefer attractive human faces. We examined whether this preference is human‐specific. Three‐ to 4‐month‐olds preferred attractive over unattractive domestic and wild cat (tiger) faces (Experiments 1 and 3). The preference was not observed when the faces were inverted, suggesting that it did not arise from low‐level image differences (Experiments 2 and 3). In addition, the spontaneous preference for attractive tiger faces influenced performance in a recognition memory task involving attractive versus unattractive tiger face pairings (Experiment 4). The findings suggest that infant preference for attractive faces reflects the activity of general processing mechanisms rather than a specific adaptation to mate choice.

Abstract Adults are sensitive to the physical differences that define ethnic groups. However, the age at which we become sensitive to ethnic differences is currently unclear. Our study aimed to clarify this by testing newborns and young infants for sensitivity to ethnicity using a visual preference (VP) paradigm. While newborn infants demonstrated no spontaneous preference for faces from either their own‐ or other‐ethnic groups, 3‐month‐old infants demonstrated a significant preference for faces from their own‐ethnic group. These results suggest that preferential selectivity based on ethnic differences is not present in the first days of life, but is learned within the first 3 months of life. The findings imply that adults' perceptions of ethnic differences are learned and derived from differences in exposure to own‐ versus other‐race faces during early development.