Comprehension and utilisation of pointing gestures and gazing in dog–human communication in relatively complex situations

The aim of the present investigation was to study the visual communication between humans and dogs in relatively complex situations. In the present research, we have modelled more lifelike situations in contrast to previous studies which often relied on using only two potential hiding locations and direct association between the communicative signal and the signalled object. In Study 1, we have provided the dogs with four potential hiding locations, two on each side of the experimenter to see whether dogs are able to choose the correct location based on the pointing gesture. In Study 2, dogs had to rely on a sequence of pointing gestures displayed by two different experimenters. We have investigated whether dogs are able to recognise an ‘indirect signal’, that is, a pointing toward a pointer. In Study 3, we have examined whether dogs can understand indirect information about a hidden object and direct the owner to the particular location. Study 1 has revealed that dogs are unlikely to rely on extrapolating precise linear vectors along the pointing arm when relying on human pointing gestures. Instead, they rely on a simple rule of following the side of the human gesturing. If there were more targets on the same side of the human, they showed a preference for the targets closer to the human. Study 2 has shown that dogs are able to rely on indirect pointing gestures but the individual performances suggest that this skill may be restricted to a certain level of complexity. In Study 3, we have found that dogs are able to localise the hidden object by utilising indirect human signals, and they are able to convey this information to their owner.     

Rats build and update topological representations through exploration

Although rats are able to build complex spatial representations of their surroundings during exploration, the nature of the encoded information is still a matter for debate. In particular, it is not well established if rats can process the topological structure of the environment in such a way that they are aware of the connections existing between remote places. Here, rats were first exposed for four 5-min trials to a complex environment divided into several sectors that were separated by doors allowing either unrestricted or restricted access to other sectors. In the fifth test trial, we measured the behavior of the animals while they explored the same environment in which, however, they faced changes that either altered or did not alter the topological structure of the environment. In experiment 1, closing previously opened doors prevented the rat from having direct access between corresponding sectors. In experiment 2, opening previously closed doors allowed direct access between sectors that had not been directly accessible. In each experiment, control doors allowed us to discard the mere influence of door manipulation. We compared the rats’ exploratory behavior in response to door manipulations that either strongly altered or did not alter the ability to commute between sectors and found evidence that the animals displayed differential reactions to the two types of door manipulations. This implies that during exploration rats build a precise map of the connectivity of space that can be flexibly updated and used for efficient navigation.     

Understanding the functional properties of tools: chimpanzees (Pan troglodytes) and capuchin monkeys (Cebus apella) attend to tool features differently

We examined whether eight capuchins and eight chimpanzees were able to retrieve a reward placed inside a tube, of varying length, by selecting the correct stick from different sets of three sticks differing in length (functional feature) and handle (non-functional feature). Moreover, to investigate whether seeing the stick inside the tube (visual feedback) improves performance, half of the subjects were tested with a transparent apparatus and the other half with an opaque apparatus. Phase 1 included (a) Training 1 in which each stick had a different handle and (b) Transfer 1 in which the handles were switched among sticks, so that the functional tool had the same length but a different handle than before. The seven chimpanzees and one capuchin that passed Transfer 1 received Transfer 2. The other subjects received (a) Training 2, which used the same sticks from Phase 1 with handles switched in every trial, and (b) Transfer 2 in which the tube was longer, all sticks had the same new handle, and the formerly longest tool became intermediate in length. Eight chimpanzees and three capuchins passed Transfer 2. Results showed that (1) chimpanzees applied relational structures in tool using tasks more quickly than capuchins and (2) capuchins required more varied experience to attend to the functional feature of the tool. Interestingly, visual feedback did not improve performance in either species.     

Ordinality and novel sequence learning in jackdaws

A hallmark of higher cognition is the flexible use of information. This requires an abstract representation of the information. In sequence learning, ordinal position knowledge is seen as a more versatile representation when compared to chaining. Here, we assessed which of these mental representations is the most natural and most dominant in jackdaws. Two jackdaws (Corvus monedula) were trained on 14 separate three-item sequences (triplets), made up of abstract images. On each trial, the three items of one triplet were presented in fixed order. The images represented either the first, second or third ordinal position. Test stimuli consisted of the three images and a distractor image that was chosen randomly from the remaining sequences. We rewarded pecking in the correct order to the images belonging to the same sequence. The most common error the birds made was to peck at a distractor item from the same ordinal position. To look at how versatile the jackdaws' ordinal knowledge was, we replaced a familiar item with a novel item in some sequences. We then created novel sequences with these items, which the birds completed correctly. It appears, then, that jackdaws have a concept of ordinal position.     

Independent effects of geometry and landmark in a spontaneous reorientation task: a study of two species of fish

While disoriented humans and animals use both landmarks and environmental geometry to guide their navigation, it is not clear what kinds of cognitive mechanisms underlie these behaviors. Because traditional tests of trained navigation behavior in environments containing both landmarks and geometric information may cloud our insight into the nature of these processes, the present study tested the spontaneous use of landmarks and environmental shape by two species of fish-Redtail Splitfins (Xenotoca eiseni) and Zebrafish (Danio rerio). The results suggest that while geometry is spontaneously used by both species and both sexes to compute relative position or direction, the spontaneous use of landmarks is limited to direct beaconing and complicated by attraction to features and variability across species and sex. These findings support the view that while multiple cues may ultimately guide behavior, the computation of orientation and relative positions is specified by geometric input and is independent from other navigation processes such as beaconing.     

Does the A-not-B error in adult pet dogs indicate sensitivity to human communication?

Recent dog-infant comparisons have indicated that the experimenter's communicative signals in object hide-and-search tasks increase the probability of perseverative (A-not-B) errors in both species (Topál et al. 2009). These behaviourally similar results, however, might reflect different mechanisms in dogs and in children. Similar errors may occur if the motor response of retrieving the object during the A trials cannot be inhibited in the B trials or if the experimenter's movements and signals toward the A hiding place in the B trials ('sham-baiting') distract the dogs' attention. In order to test these hypotheses, we tested dogs similarly to Topál et al. (2009) but eliminated the motor search in the A trials and 'sham-baiting' in the B trials. We found that neither an inability to inhibit previously rewarded motor response nor insufficiencies in their working memory and/or attention skills can explain dogs' erroneous choices. Further, we replicated the finding that dogs have a strong tendency to commit the A-not-B error after ostensive-communicative hiding and demonstrated the crucial effect of socio-communicative cues as the A-not-B error diminishes when location B is ostensively enhanced. These findings further support the hypothesis that the dogs' A-not-B error may reflect a special sensitivity to human communicative cues. Such object-hiding and search tasks provide a typical case for how susceptibility to human social signals could (mis)lead domestic dogs.     

Effects of social context and predictive relevance on action outcome monitoring

Outcome monitoring is crucial for subsequent adjustments in behavior and is associated with a specific electrophysiological response, the feedback-related negativity (FRN). Besides feedback generated by one's own action, the performance of others may also be relevant for oneself, and the observation of outcomes for others' actions elicits an observer FRN (oFRN). To test how these components are influenced by social setting and predictive value of feedback information, we compared event-related potentials, as well as their topographies and neural generators, for performance feedback generated by oneself and others in a cooperative versus competitive context. Our results show that (1) the predictive relevance of outcomes is crucial to elicit an FRN in both players and observers, (2) cooperation increases FRN and P300 amplitudes, especially in individuals with high traits of perspective taking, and (3) contrary to previous findings on gambling outcomes, oFRN components are generated for both cooperating and competing observers, but with smaller amplitudes in the latter. Neural source estimation revealed medial prefrontal activity for both FRN and oFRN, but with additional generators for the oFRN in the dorsolateral and ventral prefrontal cortex, as well as the temporoparietal junction. We conclude that the latter set of brain regions could mediate social influences on action monitoring by representing agency and social relevance of outcomes and are, therefore, recruited in addition to shared prediction error signals generated in medial frontal areas during action outcome observation.     

Electrodermal responses to sources of dual-task interference

There is a response selection bottleneck that is responsible for dual-task interference. How the response selection bottleneck operates was addressed in three dual-task experiments. The overlap between two tasks (as indexed by the stimulus onset asynchrony [SOA]) was systematically manipulated, and both reaction time and electrodermal activity were measured. In addition, each experiment also manipulated some aspect of the difficulty of either task. Both increasing task overlap by reducing SOA and increasing the difficulty of either task lengthened reaction times. Electrodermal response was strongly affected by task difficulty but was only weakly affected by SOA, and in a different manner from reaction time. A fourth experiment found that the subjectively perceived difficulty of a dual-task trial was affected both by task difficulty and by SOA, but in different ways than electrodermal activity. Overall, the results were not consistent with a response selection bottleneck that involves processes of voluntary, executive attention. Instead, the results converge with findings from neural network modeling to suggest that the delay of one task while another is being processed reflects the operation of a routing mechanism that can process only one stream of information for action at a time and of a passive, structural store that temporarily holds information for the delayed task. The results suggest that conventional blocked or event-related neuroimaging designs may be inadequate to identify the mechanism of operation of the response selection bottleneck.     

Knowledge scale effects in face recognition: An electrophysiological investigation

Although the amount or scale of biographical knowledge held in store about a person may differ widely, little is known about whether and how these differences may affect the retrieval processes triggered by the person’s face. In a learning paradigm, we manipulated the scale of biographical knowledge while controlling for a common set of minimal knowledge and perceptual experience with the faces. A few days after learning, and again after 6 months, knowledge effects were assessed in three tasks, none of which concerned the additional knowledge. Whereas the performance effects of additional knowledge were small, event-related brain potentials recorded during testing showed amplitude modulations in the time range of the N400 component—indicative of knowledge access—but also at a much earlier latency in the P100 component—reflecting early stages of visual analysis. However, no effects were found in the N170 component, which is taken to reflect structural analyses of faces. The present findings replicate knowledge scale effects in object recognition and suggest that enhanced knowledge affects both early visual processes and the later processes associated with semantic processing, even when this knowledge is not task-relevant.