“We will work for you” – Social influence may suppress individual food preferences in a communicative situation in dogs

The level of motivation (i.e. incentive power) is thought to be one of the most important factors affecting performance and learning in various tasks. We investigated whether reward quality has an effect on the performance of family dogs in a two-way object choice test in which they can find the hidden food by relying on distal momentary human pointing cues. In three experiments we varied (1) the type of food reward according to the subjects’ own preference; (2) the quality of the reward offered at the same time in the indicated and not-indicated locations; and (3) the order of the high or low quality rewards in consecutive sessions. In Experiment 1, we first tested whether dogs prefer one kind of reward over another. Then one group was tested with the ‘preferred’ food as reward in the indicated bowl, while dogs in the other group received the ‘non-preferred’ food as reward. We did not find any difference between the performance and choice latencies of the two groups. In Experiment 2 for the first group, the indicated bowl contained a piece of carrot and the not-indicated bowl was empty. In the second group the indicated bowl contained carrot, but the not-indicated bowl contained sausage. According to a preliminary preference test, most dogs prefer sausage over carrot invariably. After 20 trials, the two groups performed surprisingly similarly. There was no difference found between groups in the number of correct choices, incorrect choices and non-choices. However, the comparison between the first and last five trials revealed that subjects who found sausage when they chose the not-indicated bowl (did not follow the pointing) chose the non-indicated bowl significantly more often toward the end of their test session. In Experiment 3, each dog received two sessions with 12 pointing trials in each. For the first session, one group was rewarded with sausage and the other with carrot upon choosing the indicated bowl. In the second session, the indicated bowl contained dry dog food for both groups. We found that correct choices and response latencies did not change over two sessions in the ‘sausage’ group. In the ‘carrot’ group, the dogs chose faster in the second session, but their performance did not improve; in fact, they chose the not-indicated bowl more often than the indicated bowl. As a conclusion, we can say that reward quality had some effect on dogs’ choice behavior in these experiments. The drop in their performance was not drastic, taking into account the general refusal to eat one of the ‘rewards’ (carrot) during the preference tests and also during the test trials. It seems that incentive contrast may play a relatively minor role in dog-human social interactions. Appropriate reward quality can be very important in asocial problem solving tasks, but, when interacting with humans, following human signals may override the effect of changed incentive power.     

Positive affect and learning: exploring the “Eureka Effect” in dogs

Animals may experience positive affective states in response to their own achievements. We investigated emotional responses to problem-solving in dogs, separating these from reactions to rewards per se using a yoked control design. We also questioned whether the intensity of reaction would vary with reward type. We examined the response (behavior and heart rate) of dogs as they learned to gain access to different rewards: (1) food (2) human contact, and (3) dog contact. Twelve beagles were assigned to matched pairs, and each dog served as both an experimental and a control animal during different stages of the experiment. We trained all dogs to perform distinct operant tasks and exposed them to additional devices to which they were not trained. Later, dogs were tested in a new context. When acting as an experimental dog, access to the reward was granted immediately upon completion of trained operant tasks. When acting as a control, access to the reward was independent of the dog’s actions and was instead granted after a delay equal to their matched partner’s latency to complete their task. Thus, differences between the two situations could be attributed to experimental dogs having the opportunity to learn to control access to the reward. Experimental dogs showed signs of excitement (e.g., increased tail wagging and activity) in response to their achievements, whereas controls showed signs of frustration (e.g., chewing of the operant device) in response to the unpredictability of the situation. The intensity of emotional response in experimental dogs was influenced by the reward type, i.e., greatest response to food and least to another dog. Our results suggest that dogs react emotionally to problem-solving opportunities and that tail wagging may be a useful indicator of positive affective states in dogs.     

Cooperative problem solving by tufted capuchin monkeys (Cebus apella): spontaneous division of labor, communication, and reciprocal altruism

Using an experimentally induced cooperation task, the authors investigated whether tufted capuchin monkeys (Cebus apella) share the following 3 characteristics of cooperation with humans: division of labor, communication, and reciprocal altruism. In Experiment 1, the authors trained individual monkeys to perform the necessary sequence of actions for rewards and tested them in pairs to assess whether they could solve the task by spontaneously dividing the sequence of actions. All pairs solved this task. In Experiment 2, monkeys worked in the cooperation task and a task requiring no partner help. They looked at the partner significantly longer in the former task than in the latter, but communicative intent could not be determined. In Experiment 3, only 1 of 2 participants obtained a reward on each trial. Monkeys maintained cooperation when their roles were reversed on alternate trials. Their cooperative performances demonstrated division of labor; results suggest task-related communication and reciprocal altruism.     

Dogs are able to solve a means-end task

Dogs, although very skilled in social-communicative tasks, have shown limited abilities in the domain of physical cognition. Consequently, several researchers hypothesized that domestication enhanced dogs’ cognitive abilities in the social realm, but relaxed selection on the physical one. For instance, dogs failed to demonstrate means-end understanding, an important form of relying on physical causal connection, when tested in a string-pulling task. Here, we tested dogs in an “on/off” task using a novel approach. Thirty-two dogs were confronted with four different conditions in which they could choose between two boards one with a reward “on” and another one with a reward “off” (reward was placed next to the board). The dogs chose the correct board when (1) both rewards were placed at the same distance from the dog, when (2) the reward placed “on” the board was closer to the dog, and (3) even when the reward placed “off” the board was much closer to the dog and was food. Interestingly, in the latter case, dogs did not perform above chance, if instead of a direct reward, the dogs had to retrieve an object placed on the board to get a food reward. In contrast to previous string-pulling studies, our results show that dogs are able to solve a means-end task even if proximity of the unsupported reward is a confounding factor.     

Behavioural coordination of dogs in a cooperative problem-solving task with a conspecific and a human partner

The process of domestication has arguably provided dogs (Canis familiaris) with decreased emotional reactivity (reduced fear and aggression) and increased socio-cognitive skills adaptive for living with humans. It has been suggested that dogs are uniquely equipped with abilities that have been identified as crucial in cooperative problem-solving, namely social tolerance and the ability to attend to other individuals’ behaviour. Accordingly, dogs might be hypothesised to perform well in tasks in which they have to work together with a human partner. Recently, researchers have found that dogs successfully solved a simple cooperative task with another dog. Due to the simplicity of the task, this study was, however, unable to provide clear evidence as to whether the dogs’ successful performance was based on the cognitive ability of behavioural coordination, namely the capacity to link task requirements to the necessity of adjusting one’s actions to the partner’s behaviour. Here, we tested dogs with the most commonly used cooperative task, appropriate to test behavioural coordination. In addition, we paired dogs with both a conspecific and a human partner. Although dogs had difficulties in inhibiting the necessary action when required to wait for their partner, they successfully attended to the two cues that predicted a successful outcome, namely their partner’s behaviour and the incremental movement of rewards towards themselves. This behavioural coordination was shown with both a conspecific and a human partner, in line with the recent findings suggesting that dogs exhibit highly developed socio-cognitive skills in interactions with both humans and other dogs.     

Cooperative problem solving in African grey parrots (<Emphasis Type="Italic">Psittacus erithacus</Emphasis>)

One of the main characteristics of human societies is the extensive degree of cooperation among individuals. Cooperation is an elaborate phenomenon, also found in non-human primates during laboratory studies and field observations of animal hunting behaviour, among other things. Some authors suggest that the pressures assumed to have favoured the emergence of social intelligence in primates are similar to those that may have permitted the emergence of complex cognitive abilities in some bird species such as corvids and psittacids. In the wild, parrots show cooperative behaviours such as bi-parental care and mobbing. In this study, we tested cooperative problem solving in African grey parrots (Psittacus erithacus). Our birds were tested using several experimental setups to explore the different levels of behavioural organisation between participants, differing in temporal and spatial complexity. In our experiments, African grey parrots were able to act simultaneously but mostly failed during the delay task, maybe because of a lack of inhibitory motor response. Confronted with the possibility to adapt their behaviour to the presence or absence of a partner, they showed that they were able to coordinate their actions. They also collaborated, acting complementarily in order to solve tasks, but they were not able to place themselves in the partner’s role.     

Dogs learn to solve the support problem based on perceptual cues

Numerous recent studies have investigated how animals solve means-end tasks and unraveled considerable variation in strategies used by different species. Domestic dogs (Canis familiaris) have typically performed comparably poorly in physical cognition tasks, but a recent study showed that they can solve the on–off condition of the support problem, where they are confronted with two boards, one with a reward placed on it and the other with a reward placed next to it. To explore which strategies dogs use to solve this task, we first tested 37 dogs with the on–off condition tested previously and then tested subjects that passed this condition with three transfer tasks. For the contact condition, the inaccessible reward was touching the second board. For the perceptual containment condition, the inaccessible reward was surrounded on three sides by the second board, but not supported by it, whereas for the gap condition, discontinuous boards were used. Unlike in the previous study, our subjects did not perform above chance level in the initial trials of the on–off condition, but 13 subjects learned to solve it. Their performance in the transfer tasks suggests that dogs can learn to solve the support problem based on perceptual cues, that they can quickly adopt new cues when old ones become unreliable, but also that some apparently inherent preferences are hard to overcome. Our study contributes to accumulating evidence demonstrating that animals typically rely on a variety of perceptual cues to solve physical cognition tasks, without developing an understanding of the underlying causal structure.     

Domestic dogs (Canis familiaris) flexibly adjust their human-directed behavior to the actions of their human partners in a problem situation

Domestic dogs (Canis familiaris) have been shown to actively initiate triadic communicative interactions by looking at a human partner or by alternating their gaze between the human and an object when being faced with an out-of-reach reward or an unsolvable problem. It has hardly been investigated, however, whether dogs flexibly adjust their human-directed behavior to the actions of their partners, which indicate their willingness and abilities to help them when they are faced with a problem. Here, in two experiments, we confronted dogs—after initially allowing them to learn how to manipulate an apparatus—with two problem situations: with an empty apparatus and a blocked apparatus. In Experiment 1, we showed that dogs looked back at their owners more when the owners had previously encouraged them, independently from the problem they faced. In Experiment 2, we provided dogs with two experimenters and allowed them to learn through an initial phase that each of the experimenters could solve one of the two problems: the Filler re-baited the empty apparatus and the Helper unblocked the blocked apparatus. We found that dogs could learn to recognize the ability of the Filler and spent time close to her when the apparatus was empty. Independently from the problem, however, they always approached the Helper first. The results of the present study indicate that dogs may have a limited understanding of physical problems and how they can be solved by a human partner. Nevertheless, dogs are able to adjust their behavior to situation-specific characteristics of their human partner’s behavior.     

Differential dependence of Pavlovian incentive motivation and instrumental incentive learning processes on dopamine signaling

Here we attempted to clarify the role of dopamine signaling in reward seeking. In Experiment 1, we assessed the effects of the dopamine D(1)/D(2) receptor antagonist flupenthixol (0.5 mg/kg i.p.) on Pavlovian incentive motivation and found that flupenthixol blocked the ability of a conditioned stimulus to enhance both goal approach and instrumental performance (Pavlovian-to-instrumental transfer). In Experiment 2 we assessed the effects of flupenthixol on reward palatability during post-training noncontingent re-exposure to the sucrose reward in either a control 3-h or novel 23-h food-deprived state. Flupenthixol, although effective in blocking the Pavlovian goal approach, was without effect on palatability or the increase in reward palatability induced by the upshift in motivational state. This noncontingent re-exposure provided an opportunity for instrumental incentive learning, the process by which rats encode the value of a reward for use in updating reward-seeking actions. Flupenthixol administered prior to the instrumental incentive learning opportunity did not affect the increase in subsequent off-drug reward-seeking actions induced by that experience. These data suggest that although dopamine signaling is necessary for Pavlovian incentive motivation, it is not necessary for changes in reward experience, or for the instrumental incentive learning process that translates this experience into the incentive value used to drive reward-seeking actions, and provide further evidence that Pavlovian and instrumental incentive learning processes are dissociable.     

A Description–Experience Gap in Social Interactions: Information about Interdependence and Its Effects on Cooperation

In social interactions, decision makers are often unaware of their interdependence with others, precluding the realization of shared long‐term benefits. In an experiment, pairs of participants played an Iterated Prisoner's Dilemma under various conditions involving differing levels of interdependence information. Each pair was assigned to one of four conditions: “No‐Info” players saw their own actions and outcomes, but were not told that they interacted with another person; “Min‐Info” players knew they interacted with another person but still without seeing the other's actions or outcomes; “Mid‐Info” players discovered the other's actions and outcomes as they were revealed over time; and “Max‐Info” players were also shown a complete payoff matrix mapping actions to outcomes from the outset and throughout the game. With higher levels of interdependence information, we found increased individual cooperation and mutual cooperation, driven by increased reciprocating cooperation (in response to a counterpart's cooperation). Furthermore, joint performance and satisfaction were higher for pairs with more information. We discuss how awareness of interdependence may encourage cooperative behavior in real‐world interactions. Copyright © 2013 John Wiley & Sons, Ltd.     

The interaction between self-bias and reward: Evidence for common and distinct processes

The perceptual matching of shapes and labels can be affected by both self- and reward-biases when shapes are linked either to labels referring to particular individuals (you, friend, stranger) or to different reward values (£8, £2, £0). We investigated the relations between these biases by varying the reward value associated with particular shape–label pairs (circle–you, square–friend, triangle–stranger). Self shape–label pairs (circle–you) always received no reward, while friend shape–label pairs (square–friend) received high reward and stranger shape–label pairs low reward (triangle–stranger), or the reverse (friend—low reward; stranger—high reward). Despite receiving no reward, responses to self-related pairs were advantaged relative to those to low-reward stimuli and did not differ from those to high-reward items. There was also an advantage for responses to high-reward friend pairs relative to low-reward stranger stimuli, and for high-reward stranger stimuli compared to low-reward friends. Correlations across individuals were found across trial blocks for both the self-advantage and the high-reward advantage, but the self- and reward-advantages were uncorrelated. This suggests that the self- and reward-advantage effects have different origins. In addition, the magnitude of the self-advantage varied according to the rated personal distance between a participant and a stranger. For individuals manifesting a close personal distance to strangers, the self-advantage was smaller, and sensitivity to reward influenced the difference between the self- and high-reward conditions. For individuals manifesting a large personal distance to strangers, sensitivity to reward did not affect self-matching. We suggest that self-advantages on perceptual matching arise independent of reward for individuals with a large personal distance to strangers. On the other hand, in individuals with a weak self-bias, high reward and the self modulate a common subjective value system.     

Two‐year‐old children but not domestic dogs understand communicative intentions without language,gestures, or gaze

Infants can see someone pointing to one of two buckets and infer that the toy they are seeking is hidden inside. Great apes do not succeed in this task, but, surprisingly, domestic dogs do. However, whether children and dogs understand these communicative acts in the same way is not yet known. To test this possibility, an experimenter did not point, look, or extend any part of her body towards either bucket, but instead lifted and shook one via a centrally pulled rope. She did this either intentionally or accidentally, and did or did not address her act to the subject using ostensive cues. Young 2‐year‐old children but not dogs understood the experimenter's act in intentional conditions. While ostensive pulling of the rope made no difference to children's success, it actually hindered dogs' performance. We conclude that while human children may be capable of inferring communicative intent from a wide variety actions, so long as these actions are performed intentionally, dogs are likely to be less flexible in this respect. Their understanding of communicative intention may be more dependent upon bodily markers of communicative intent, including gaze, orientation, extended limbs, and vocalizations. This may be because humans have come under selective pressure to develop skills for communicating with absent interlocutors – where bodily co‐presence is not possible.     

How do students improve their value-based learning with task experience?

When learning items that vary in reward, students improve their scores (i.e., earned reward) with task experience. In four experiments, we examined whether such improvements arise from better selective encoding of items that would earn more (vs. less) reward. Participants studied and recalled words across multiple study-test trials. On each trial, 12 words were slated with different values (typically from 1 to 12), and participants earned the point value assigned to a given word if it was correctly recalled. In all experiments, participants earned more points across the first two trials. In Experiment 1, participants either self-paced their study or had experimenter-paced study and in Experiment 2, some participants were penalised for each second spent during study. Improvements in points earned were related to increases in overall recall but not to selective encoding. In Experiment 3, some participants were given value-emphasised instructions, yet they did not demonstrate selective encoding. In Experiment 4, we used a larger range of point values, but selective encoding still did not account for the improvement in point scores across lists. These results suggest that metacognitively-driven selective encoding is not necessary to observe improvements in value-based learning.     

Waiting for more: the performance of domestic dogs (Canis familiaris) on exchange tasks

Five domestic dogs (Canis familiaris) were tested in a cooperative exchange task with an experimenter, as previously tested in non-human primates. In the first task, the dogs exchanged to maximise payoffs when presented with food items of differing quality. All consistently exchanged lower-value for higher-value rewards, as determined by their individual food preference, and exchanges corresponded significantly with the spontaneous preferences of three dogs. Next, all subjects demonstrated an ability to perform two and three exchanges in succession, to gain both qualitative and quantitatively increased rewards (group mean = 72 and 92% successful triple exchanges, respectively). Finally, the ability to delay gratification over increasing intervals was tested; the dogs kept one food item to exchange later for a larger item. As previously reported in non-human primates, there was considerable individual variation in the tolerance of delays, between 10 s and 10 min for the largest rewards. For those who reached longer time lags (>40 s), the dogs gave up the chance to exchange earlier than expected by each subject’s general waiting capacity; the dogs anticipated delay duration and made decisions according to the relative reward values offered. Compared to primates, dogs tolerated relatively long delays for smaller value rewards, suggesting that the socio-ecological history of domestic dogs facilitates their performance on decision-making and delay of gratification tasks.     

Let the force be with us: dyads exploit haptic coupling for coordination

People often perform actions that involve a direct physical coupling with another person, such as when moving furniture together. Here, we examined how people successfully coordinate such actions with others. We tested the hypothesis that dyads amplify their forces to create haptic information to coordinate. Participants moved a pole (resembling a pendulum) back and forth between two targets at different amplitudes and frequencies. They did so by pulling on cords attached to the base of the pole, one on each side. In the individual condition, one participant performed this task bimanually, and in the joint condition two participants each controlled one cord. We measured the moment-to-moment pulling forces on each cord and the pole kinematics to determine how well individuals and dyads performed. Results indicated that dyads produced much more overlapping forces than individuals, especially for tasks with higher coordination requirements. Thus, the results suggest that dyads amplify their forces to generate a haptic information channel. This likely reflects a general coordination principle in haptic joint action, where force amplification allows dyads to perform at the same level as individuals.     

Cooperative Learning Strategies in Processing Descriptive Text: Effects of Role Activity Level of the Learner

The dyadic cooperative learning situation was examined by analyzing the impact of specific roles and activities on each member of the dyad. In learning scientific text passages, one member of the cooperating pair served as a recaller/oral summarizer and the other pair member served as either an active or passive listener/facilitator. Members of some treatment conditions alternated recaller and listener roles, while those in other conditions had fixed roles. Serving as a no-treatment control, students in one group used their own study techniques. The results indicated that both roles (fixed vs. alternating) and listener activities (active vs. passive) are important variables in cooperative learning. On free recall of text main ideas, fixed recallers outperformed fixed listeners, and pairs incorporating an active listener outperformed those that did not. Certain combinations of role and listener activity resulted in better performance than that achieved by individuals using their own study methods. Additionally, persons who alternated recaller/listener roles subjectively evaluated the cooperative learning experience more positively than the cooperative groups.     

Probability-reward preferences of rhesus monkeys

The relative preferences of rhesus monkeys for reward probability versus amount were investigated with procedures which contrasted general experience with specific instructions, and evaluated the relationship between probability-amount combinations and preference strength. Four stimulus objects, each signifying a different combination of reward frequency and amount (100% with one unit; 50% with two units; 33% with three units; or 25% with four units), were presented in pairs, one pair per daily session, with trial schedules providing the same amount of reward within each set of 12 trials. In Phase A, 4 monkeys (Group 1) were tested on the six choice-pairs with no preliminary training. In Phase B, Group 1 was joined by an additional 4 monkeys (Group 2), and each of the tasks was preceded by a demonstration of the relevant stimuli, one at a time, together with their associated probabilities and amounts. Group 1 animals developed preferences during Phase A for the more frequently rewarded objects, which persisted into Phase B, whereas Group 2 animals showed no preferences. This result indicates that preliminary instructions concerning the reward combinations associated with stimulus objects can prevent the development of a preference for greater probability over greater amount of reward, but cannot extinguish it once it has been formed or reestablished within the context of a particular task.     

Dichotomous perception of animal categories in infancy

ABSTRACT

Although there is a wealth of knowledge on categorization early in life, there are still many unanswered questions about the nature of category representation in infancy. For example, it is unclear whether infants are sensitive to boundaries between complex categories, such as types of animals, or whether young infants exhibit such sensitivity without explicit experience in the lab. Using a morphing technique, we linearly altered the category composition of images and measured 6.5-month-olds’ attention to pairs of animal faces that either did or did not cross the categorical boundary, with the stimuli in each pair being equally dissimilar from one another across the two types of image pairs. Results indicated that infants dichotomize the continua between cats and dogs and between cows and otters, but only when the images are presented in their canonical, upright orientations. These findings demonstrate a propensity to dichotomize early in life that could have implications for social categorizations, such as race and gender.     

Uses of double-pulse stimulation behaviorally to infer refractoriness, summation, convergence, and transmitter characteristics of hypothalamic reward systems.

To self-administer trains of pulse pairs, rats with electrodes in the hypothalamic reward system would press a lever at lower current thresholds or faster latencies, the shorter the intrapair interval--unless the interval was so short that each second pulse fell within the refractory period following the first. By delivering all second pulses to the contralateral reward system not only was this refractory period limitation on temporal summation circumvented but spatial summation of the two reward systems was demonstrated. Evidently, they converge somewhere upon common neurons. Nearby nonreward structures did not share in this convergence. Assuming that the temporal-summation decline at longer intrapair intervals reflected the course of transmitter disposal at the synapse, imipramine and diisopropylfluorophosphate were peripherally administered. These drugs, which retard disposal, respectively, in adrenergic and cholinergic synapses, indeed prolonged temporal summation, thus, supporting the assumption and implying that adrenergic and cholinergic mechanisms both mediate self-stimulation.     

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.