Dingoes (Canis dingo) can use human social cues to locate hidden food

There is contention concerning the role that domestication plays in the responsiveness of canids to human social cues, with most studies investigating abilities of recognized domestic dog breeds or wolves. Valuable insight regarding the evolution of social communication with humans might be gained by investigating Australian dingoes, which have an early history of domestication, but have been free-ranging in Australia for approximately 3500–5000 years. Seven ‘pure’ dingoes were tested outdoors by a familiar experimenter using the object-choice paradigm to determine whether they could follow nine human communicative gestures previously tested with domestic dogs and captive wolves. Dingoes passed all cues significantly above control, including the “benchmark” momentary distal pointing, with the exception of gaze only, gaze and point, and pointing from the incorrect location. Dingo performance appears to lie somewhere between wolves and dogs, which suggests that domestication may have played a role in their ability to comprehend human gestures.     

The evil eye: Eye gaze and competitiveness in social decision making

We demonstrate that a person's eye gaze and his/her competitiveness are closely intertwined in social decision making. In an exploratory examination of this relationship, Study 1 uses field data from a high‐stakes TV game show to demonstrate that the frequency by which contestants gaze at their opponent's eyes predicts their defection in a variant on the prisoner's dilemma. Studies 2 and 3 use experiments to examine the underlying causality and demonstrate that the relationship between gazing and competitive behavior is bi‐directional. In Study 2, fixation on the eyes, compared to the face, increases competitive behavior toward the target in an ultimatum game. In Study 3, we manipulate the framing of a negotiation (cooperative vs. competitive) and use an eye tracker to measure fixation number and time spent fixating on the counterpart's eyes. We find that a competitive negotiation elicits more gazing, which in turn leads to more competitive behavior.     

Cues to food location that domestic dogs (Canis familiaris) of different ages do and do not use

The results of three experiments are reported. In the main study, a human experimenter presented domestic dogs (Canis familiaris) with a variety of social cues intended to indicate the location of hidden food. The novel findings of this study were: (1) dogs were able to use successfully several totally novel cues in which they watched a human place a marker in front of the target location; (2) dogs were unable to use the marker by itself with no behavioral cues (suggesting that some form of human behavior directed to the target location was a necessary part of the cue); and (3) there were no significant developments in dogs’ skills in these tasks across the age range 4 months to 4 years (arguing against the necessity of extensive learning experiences with humans). In a follow-up study, dogs did not follow human gaze into “empty space” outside of the simulated foraging context. Finally, in a small pilot study, two arctic wolves (Canis lupus) were unable to use human cues to locate hidden food. These results suggest the possibility that domestic dogs have evolved an adaptive specialization for using human-produced directional cues in a goal-directed (especially foraging) context. Exactly how they understand these cues is still an open question. Received: 28 April 2000 / Accepted after revision: 2 September 2000     

Look into my eyes: Gaze direction and person memory

The current research considered the effects of gaze direction on a fundamental aspect of social cogition: person memory. It was anticipated that a person's direction of gaze (i.e., direct or averted) would impact his or her subsequent memorability, such that recognition would be enhanced for targets previously displaying direct gaze. In Experiment 1, participants were presented with faces displaying either direct or averted gaze in a person‐classification (i.e., conceptual) task. Then, in a surprise memory test, they were required to report whether a presented face had been seen before. As expected, a recognition advantage was observed for targets displaying direct gaze during the initial classification task. This finding was replicated and extended in a second experiment in which participants initially reported the spatial location (i.e., perceptual task) of each face. We consider the implications of these findings for basic aspects of social‐cognitive functioning and person perception.     

Contrast polarity of eyes modulates gaze‐cueing effect1

Two experiments using a modified Posner‐type visual cueing paradigm tested the prediction that detecting the darker region of the eyes of another's gaze triggers a reflexive orienting of the observer in the direction of the gaze. A target was presented in the left or right visual‐field following a gaze‐cue with positive or negative‐image polarity (Experiment 1). In Experiment 2, the polarity of the eyes was manipulated independently of the negative polarity of the face (eye‐positive or eye‐negative‐image polarity conditions). The results showed that the response to the target presented at the side the eyes gazed toward was faster than for the target presented at the other side in the positive polarity condition (Experiment 1), whereas, in the negative polarity condition, the gaze‐cuing effect was not found. In Experiment 2, in the eye‐negative condition, a reversed gaze‐cueing effect appeared, whereas in the eye‐positive polarity condition, a typical gaze‐cueing effect was obtained. These findings suggested that the reflexive orienting of the observer shifts toward the position indicated by the darker region of the other's eyes.     

Face learning with multiple images leads to fast acquisition of familiarity for specific individuals

Matching unfamiliar faces is a difficult task. Here we ask whether it is possible to improve performance by providing multiple images to support matching. In two experiments we observe that accuracy improves as viewers are provided with additional images on which to base their match. This technique leads to fast learning of an individual, but the effect is identity-specific: Despite large improvements in viewers’ ability to match a particular person's face, these improvements do not generalize to other faces. Experiment 2 demonstrated that trial-by-trial feedback provided no additional benefits over the provision of multiple images. We discuss these results in terms of familiar and unfamiliar face processing and draw out some implications for training regimes.     

Facing away from the interviewer: Evidence of little benefit to eyewitnesses' memory performance

Averting gaze from another person's face generally improves cognitive performance, yet, little is known about how witnesses' gaze direction affects their recall during investigative interviews. Here, participants witnessed a video-recorded incident, and were interviewed via free recall and closed questions following a short delay. In Experiment 1, participants either faced the interviewer or faced away during the interview. In Experiment 2, alongside this manipulation, the interviewer also either faced the witness or faced away. In Experiment 3, witness gaze direction was manipulated alongside rapport-building. In Experiment 4, the effect of facing away was directly compared with that of eye-closure. Mini meta-analysis of all four experiments showed that the effect of witness gaze direction on memory performance was minimal. Furthermore, neither aversion of interviewer's gaze nor rapport-building magnified this effect. Added to the cumulative literature on eyewitness gaze aversion, these findings afford better estimates of the likely size of these effects.     

Differences in problem-solving between canid populations: Do domestication and lifetime experience affect persistence?

Past research has suggested that a variety of factors, phylogenetic and ontogenetic, play a role in how canines behave during problem-solving tasks and the degree to which the presence of a human influences their problem-solving behaviour. While comparisons between socialized wolves and domestic dogs have commonly been used to tease apart these predictive factors, in many cases a single dog population, often pets, have been used for these comparisons. Less is understood about how different populations of dogs may behave when compared with wolves, or with each other, during an independent problem-solving task. This experiment compared the independent persistence of four populations of canines (two groups of pet domestic dogs, a group of free-ranging domestic dogs, and human-socialized wolves) on an independent problem-solving task in the presence of an on looking human. Results showed that wolves persisted the most at the task while free-ranging dogs persisted the least. Free-ranging dogs gazed at the human experimenter for the longest durations during the task. While further research is needed to understand why these differences exist, this study demonstrates that dogs, even those living outside human homes as scavengers, show comparatively low levels of persistence when confronted with a solvable task in the presence of a human as well as significantly greater duration of human-directed gaze when compared with wolves.     

Effects of gaze‐aversion on visual‐spatial imagination

Research suggests that averting gaze from an interlocutor can improve both children's and adults' performance in a range of cognitive tasks. With the present experiments, we investigated the effect of gaze aversion on adults' visual‐spatial imagination, using a methodology adapted from Kerr (1987). Participants mentally kept track of a pathway through an imaginary matrix, while either maintaining eye‐contact with the experimenter, closing their eyes, gazing at a static or a dynamic visual stimulus (in Experiment 1), or fixating an upright or inverted image of the experimenter's face (in Experiment 2). The results show that whereas maintaining eye‐contact with another person disrupts accurate imagination of this pathway, averting gaze or looking at other visual stimuli does not. We conclude that gaze aversion benefits cognitive performance, not just by disengaging visual attention from irrelevant visual information, but also by interrupting social interaction processes involved in face‐to‐face communication.     

Does affective information influence domestic dogs’ (<Emphasis Type="Italic">Canis lupus familiaris</Emphasis>) point-following behavior?

Several studies have examined dogs’ (Canis lupus familiaris) comprehension and use of human communicative cues. Relatively few studies have, however, examined the effects of human affective behavior (i.e., facial and vocal expressions) on dogs’ exploratory and point-following behavior. In two experiments, we examined dogs’ frequency of following an adult’s pointing gesture in locating a hidden reward or treat when it occurred silently, or when it was paired with a positive or negative facial and vocal affective expression. Like prior studies, the current results demonstrate that dogs reliably follow human pointing cues. Unlike prior studies, the current results also demonstrate that the addition of a positive affective facial and vocal expression, when paired with a pointing gesture, did not reliably increase dogs’ frequency of locating a hidden piece of food compared to pointing alone. In addition, and within the negative facial and vocal affect conditions of Experiment 1 and 2, dogs were delayed in their exploration, or approach, toward a baited or sham-baited bowl. However, in Experiment 2, dogs continued to follow an adult’s pointing gesture, even when paired with a negative expression, as long as the attention-directing gesture referenced a baited bowl. Together these results suggest that the addition of affective information does not significantly increase or decrease dogs’ point-following behavior. Rather these results demonstrate that the presence or absence of affective expressions influences a dogs’ exploratory behavior and the presence or absence of reward affects whether they will follow an unfamiliar adult’s attention-directing gesture.     

Comprehension of human pointing gestures in young human-reared wolves (<Emphasis Type="Italic">Canis lupus</Emphasis>) and dogs (<Emphasis Type="Italic">Canis familiaris</Emphasis>)

Dogs have a remarkable skill to use human-given cues in object-choice tasks, but little is known to what extent their closest wild-living relative, the wolf can achieve this performance. In Study 1, we compared wolf and dog pups hand-reared individually and pet dogs of the same age in their readiness to form eye-contact with a human experimenter in an object-choice task and to follow her pointing gesture. The results showed that dogs already at 4 months of age use momentary distal pointing to find hidden food even without intensive early socialization. Wolf pups, on the contrary, do not attend to this subtle pointing. Accordingly in Studies 2 and 3, these wolves were tested longitudinally with this and four other (easier) human-given cues. This revealed that wolves socialized at a comparable level to dogs are able to use simple human-given cues spontaneously if the human’s hand is close to the baited container (e.g. touching, proximal pointing). Study 4 showed that wolves can follow also momentary distal pointing similarly to dogs if they have received extensive formal training. Comparing the wolves to naïve pet dogs of the same age revealed that during several months of formal training wolves can reach the level of dogs in their success of following momentary distal pointing in parallel with improving their readiness to form eye-contact with a human experimenter. We assume that the high variability in the wolves’ communicative behaviour might have provided a basis for selection during the course of domestication of the dog.     

Not afraid to trust you: Trustworthiness moderates gaze cueing but not in highly anxious participants

Gaze cueing (i.e., the shifting of person B's attention by following person A's gaze) is closely linked with human interaction and learning. To make the most of this connection, researchers need to investigate possible moderators enhancing or reducing the extent of this attentional shifting. In this study we used a gaze cueing paradigm to demonstrate that the perceived trustworthiness of a cueing person constitutes such a moderator for female participants. Our results show a significant interaction between perceived trustworthiness and the response time trade-off between valid and invalid gaze cues [gaze cueing effect (GCE)], as manifested in greater following of a person's gaze if this person was trustworthy as opposed to the following of an untrustworthy person's gaze. An additional exploratory analysis showed potentially moderating influences of trait-anxiety on this interaction (p = .057). The affective background of the experiment (i.e., using positive or negative target stimuli) had no influence.     

Electrophysiological responses in mothers to their own and unfamiliar child's gaze information

An attachment bond between a mother and her child is one of the most intimate human relationships. It is important for a mother to be sensitive to her child's gaze direction because exchanging gaze information plays a vital role in their relationship. Furthermore, recent studies have revealed differential neural activation patterns in mothers when presented the faces of their own children or the unfamiliar child of other people. Based on these findings, in the present study, we investigated whether mothers show differential neural responses to gaze information of their own child compared to that of an unfamiliar child. To this end, event-related-potentials elicited by the faces of one's own or an unfamiliar child with straight or averted gaze directions were measured using an oddball-paradigm. The results showed that peak amplitudes of the N170 component were enlarged by viewing the straight gazes compared to the averted gazes of one's own child, but not of an unfamiliar child. When the gaze was directed straight, the P3 amplitude elicited by one's own child's face is smaller than that elicited by an unfamiliar child's face. P3s elicited in viewing one's own child's face with averted gaze and in viewing an unfamiliar child's face with straight gaze were positively correlated with state-anxiety. These results bolster the hypothesis that processing the gaze information of one's own child elicits differential neural activation compared to the gaze information of an other person's unfamiliar child at both perceptual and evaluative stages of face processing.     

A comparative study of the use of visual communicative signals in interactions between dogs (Canis familiaris) and humans and cats (Felis catus) and humans

Dogs' (Canis familiaris) and cats' (Felis catus) interspecific communicative behavior toward humans was investigated. In Experiment 1, the ability of dogs and cats to use human pointing gestures in an object-choice task was compared using 4 types of pointing cues differing in distance between the signaled object and the end of the fingertip and in visibility duration of the given signal. Using these gestures, both dogs and cats were able to find the hidden food; there was no significant difference in their performance. In Experiment 2, the hidden food was made inaccessible to the subjects to determine whether they could indicate the place of the hidden food to a naive owner. Cats lacked some components of attention-getting behavior compared with dogs. The results suggest that individual familiarization with pointing gestures ensures high-level performance in the presence of such gestures; however, species-specific differences could cause differences in signaling toward the human.     

Learning unfamiliar faces in infants: The advantage of the regular sequence presentation and the three‐quarter view superiority

We investigated the effect of the regular sequence of different views and the three‐quarter view effect on the learning of unfamiliar faces by infants. 3–8‐month‐old infants were familiarized with unfamiliar female faces in either the regular condition (presenting 11 different face views from the frontal view to the left‐side profile view in regular order) or the random condition (presenting the same 11 different face views in random order). Following the familiarization, infants were tested with a pair of a familiarized and a novel female face either in a three‐quarter (Experiment 1) or in a profile view (Experiment 2). Results showed that only 6–8‐month‐old infants could identify a familiarized face in the regular condition when they were tested in three‐quarter views. In contrast, 6–8‐month‐old infants showed no significant novelty preference in profile views. The results suggest that the regular sequence of different face views promotes the learning of unfamiliar faces by infants over 6 months old. Moreover, our findings imply that the three‐quarter view effect appears in infants.     

Attributing attention: the use of human-given cues by domestic horses (Equus caballus)

Recent research has shown that domestic dogs are particularly good at determining the focus of human attention, often outperforming chimpanzees and hand-reared wolves. It has been suggested that the close evolutionary relationship between humans and dogs has led to the development of this ability; however, very few other domestic species have been studied. We tested the ability of 36 domestic horses to discriminate between an attentive and inattentive person in determining whom to approach for food. The cues provided were body orientation, head orientation or whether the experimenters’ eyes were open or closed. A fourth, mixed condition was included where the attentive person stood with their body facing away from the subjects but their head turned towards the subject while the inattentive person stood with their body facing the subject but their head turned away. Horses chose the attentive person significantly more often using the body cue, head cue, and eye cue but not the mixed cue. This result suggests that domestic horses are highly sensitive to human attentional cues, including gaze. The possible role of evolutionary and environmental factors in the development of this ability is discussed.     

Dogs can discriminate human smiling faces from blank expressions

Dogs have a unique ability to understand visual cues from humans. We investigated whether dogs can discriminate between human facial expressions. Photographs of human faces were used to test nine pet dogs in two-choice discrimination tasks. The training phases involved each dog learning to discriminate between a set of photographs of their owner’s smiling and blank face. Of the nine dogs, five fulfilled these criteria and were selected for test sessions. In the test phase, 10 sets of photographs of the owner’s smiling and blank face, which had previously not been seen by the dog, were presented. The dogs selected the owner’s smiling face significantly more often than expected by chance. In subsequent tests, 10 sets of smiling and blank face photographs of 20 persons unfamiliar to the dogs were presented (10 males and 10 females). There was no statistical difference between the accuracy in the case of the owners and that in the case of unfamiliar persons with the same gender as the owner. However, the accuracy was significantly lower in the case of unfamiliar persons of the opposite gender to that of the owner, than with the owners themselves. These results suggest that dogs can learn to discriminate human smiling faces from blank faces by looking at photographs. Although it remains unclear whether dogs have human-like systems for visual processing of human facial expressions, the ability to learn to discriminate human facial expressions may have helped dogs adapt to human society.     

The effects of adults' affective expression and direction of visual gaze on 12‐month‐olds' visual preferences for an object following a 5‐minute, 1‐day,or 1‐month delay

Between 12‐ and 14 months of age infants begin to use another's direction of gaze and affective expression in learning about various objects and events. What is not well understood is how long infants' behaviour towards a previously unfamiliar object continues to be influenced following their participation in circumstances of social referencing. In this experiment, we examined infants' sensitivity to an adult's direction of gaze and their visual preference for one of two objects following a 5‐min, 1‐day, or 1‐month delay. Ninety‐six 12‐month‐olds participated. For half of the infants during habituation (i.e., familiarization), the adults' direction of gaze was directed towards an unfamiliar object (look condition). For the remaining half of the infants during habituation, the adults' direction of gaze was directed away from the unfamiliar object (look‐away condition). All infants were habituated to two events. One event consisted of an adult looking towards (look condition) or away from (look‐away condition) an object while facially and vocally conveying a positive affective expression. The second event consisted of the same adult looking towards or away from a different object while conveying a disgusted affective expression. Following the habituation phase and a 5‐min, 1‐day, or 1‐month delay, infants' visual preference was assessed. During the visual preference phase, infants saw the two objects side by side where the adult conveying the affective expression was not visible. Results of the visual preference phase indicate that infants in the look condition showed a significant preference for object previously paired with the positive affect following a 5‐min and 1‐day delay. No significant visual preference was found in the look condition following a 1‐month delay. No significant preferences were found at any retention interval in the look‐away condition. Results are discussed in terms of early learning, social referencing, and early memory.     

The effect of changes in posture and clothing on the development of unfamiliar person recognition

In contrast to face recognition little is known about the development of unfamiliar whole‐person recognition. Various cues in a person's appearance may contribute to recognition performance. An age‐related influence of different features on person recognition performance is possible. Here, we investigated two variable features of person recognition, namely posture and clothing, in 4‐year‐olds, 6‐year‐olds, 8‐year‐olds, 10‐year‐olds and adults. The experimental methodology of a short‐term recognition‐test with an immediate four alternative forced choice (4AFC)‐array was used. Targets were shown for 5 seconds. Experiment 1 clearly indicates that a variation of both posture and clothing decreases performance in all age groups compared to a standard, i.e. a no‐change condition. An interaction age×variation of posture and clothing was not observed. In order to untangle the two aspects of posture and clothing, Experiment 2 varied only posture between encoding and recognition. An age‐effect was shown, but no other significant result occurred. Experiment 3 investigated variation of clothing only, and found main effects of clothing and age. Because there was no interaction between the two factors we infer that a change of clothing impairs all subjects' recognition performance. Children's person recognition performance suffers in a way similar to adults' person recognition performance when clothing is varied. In contrast, changing posture does not necessarily decrease recognition accuracy, neither in children nor in adults. No developmental gains were found for dealing with the transformation of posture and clothing between the encoding and recognition phase. Copyright © 2003 John Wiley & Sons, Ltd.     

Physical self-similarity enhances the gaze-cueing effect

Important social information can be gathered from the direction of another person's gaze, such as their intentions and aspects of the environment that are relevant to those intentions. Previous work has examined the effect of gaze on attention through the gaze-cueing effect: an enhancement of performance in detecting targets that appear where another person is looking. The present study investigated whether the physical self-similarity of a face could increase its impact on attention. Self-similarity was manipulated by morphing participants' faces with those of strangers. The effect of gaze direction on target detection was strongest for faces morphed with the participant's face. The results support previous work suggesting that self-similar faces are processed differently from dissimilar faces. The data also demonstrate that a face's similarity to one's own face influences the degree to which that face guides our attention in the environment.