Exploring individual and social learning in jackdaws (Corvus monedula).

Information about novel environments or foods can be gathered via individual or social learning. Whereas individual learning is assumed to be more costly and less effective than social learning, it also yields more detailed information. Juveniles are often found to be more explorative than adults. Still under the protection of their parents, this allows them to sample their environment in preparation for later in life. We tested individual and social learning in jackdaws (Corvus monedula) of different age groups in a semi-natural group setting. Juvenile and adult jackdaws differed in their learning propensity. Juveniles spent more time at the test apparatus, were more explorative, and caused the apparatus to open. Almost all the openings at the apparatus matched the demonstrated method. As more observers became available, the juveniles could observe each other. Individuals preferentially watched successful conspecifics and those they could scrounge food from. Lower-ranking individuals tended to watch higher ranking ones; higher ranking individuals preferentially watched conspecifics of similar rank. The control group did not manipulate the apparatus. Due to the lack of this baseline, it was difficult to determine for certain whether the opening technique was acquired via individual or social learning. We conclude that if social learning played a role, the underlying mechanism was most likely local or stimulus enhancement. It is, however, more parsimonious to assume that juveniles were more explorative than adults, and that their opening technique was potentially easier to acquire than the one demonstrated to adults.

Adjusting foraging strategies: a comparison of rural and urban common mynas (Acridotheres tristis).

Establishment in urbanized environments is associated with changes in physiology, behaviour, and problem-solving. We compared the speed of learning in urban and rural female common mynas, Acridotheres tristis, using a standard visual discrimination task followed by a reversal learning phase. We also examined how quickly each bird progressed through different stages of learning, including sampling and acquisition within both initial and reversal learning, and persistence following reversal. Based on their reliance on very different food resources, we expected urban mynas to learn and reversal learn more quickly but to sample new contingencies for proportionately longer before learning them. When quantified from first presentation to criterion achievement, urban mynas took more 20-trial blocks to learn the initial discrimination, as well as the reversed contingency, than rural mynas. More detailed analyses at the level of stage revealed that this was because urban mynas explored the novel cue-outcome contingencies for longer, and despite transitioning faster through subsequent acquisition, remained overall slower than rural females. Our findings draw attention to fine adjustments in learning strategies in response to urbanization and caution against interpreting the speed to learn a task as a reflection of cognitive ability.

Reasoning by exclusion in the kea (Nestor notabilis).

Reasoning by exclusion, i.e. the ability to understand that if there are only two possibilities and if it is not A, it must be B, has been a topic of great interest in recent comparative cognition research. Many studies have investigated this ability, employing different methods, but rarely exploring concurrent decision processes underlying choice behaviour of non-human animals encountering inconsistent or incomplete information. Here, we employed a novel training and test method in order to perform an in-depth analysis of the underlying processes. Importantly, to discourage the explorative behaviour of the kea, a highly neophilic species, the training included a large amount of novel, unrewarded stimuli. The subsequent test consisted of 30 sessions with different sequences of four test trials. In these test trials, we confronted the kea with novel stimuli that were paired with either the rewarded or unrewarded training stimuli or with the novel stimuli of previous test trials. Once habituated to novelty, eight out of fourteen kea tested responded to novel stimuli by inferring their contingency via logical exclusion of the alternative. One individual inferred predominantly in this way, while other response strategies, such as one trial learning, stimulus preferences and avoiding the negative stimulus also guided the responses of the remaining individuals. Interestingly, the difficulty of the task had no influence on the test performance. We discuss the implications of these findings for the current hypotheses about the emergence of inferential reasoning in some avian species, considering causal links to brain size, feeding ecology and social complexity.

Do monkeys compare themselves to others?

Social comparisons are a fundamental characteristic of human behaviour, yet relatively little is known about their evolutionary foundations. Adapting the co-acting paradigm from human research (Seta in J Pers Soc Psychol 42:281-291, 1982. doi: 10.1037//0022-3514.42.2.281), we examined how the performance of a partner influenced subjects' performance in long-tailed macaques (Macaca fascicularis). Using parallel testing in touch screen setups in which subjects had to discriminate familiar and novel photographs of men and women, we investigated whether accuracy and reaction time were influenced by partner performance and relationship quality (affiliate vs. non-affiliate). Auditory feedback about the alleged performance of the co-actor was provided via playback; partner performance was either moderately or extremely better or worse than subject performance. We predicted that subjects would assimilate to moderately different comparison standards as well as to affiliates and contrast away from extreme standards and non-affiliates. Subjects instantly generalized to novel pictures. While accuracy was not affected by any of the factors, long reaction times occurred more frequently when subjects were tested with a non-affiliate who was performing worse, compared to one who was doing better than them (80% quantile worse: 5.1, better: 4.3 s). For affiliate co-actors, there was no marked effect (worse: 4.4, better: 4.6 s). In a control condition with no auditory feedback, subjects performed somewhat better in the presence of affiliates (M = 77.8% correct) compared to non-affiliates (M = 71.1%), while reaction time was not affected. Apparently, subjects were sensitive to partner identity and performance, yet variation in motivation rather than assimilation and contrast effects may account for the observed effects.

Long-term effectiveness of a hyaluronic acid soft tissue filler in patients with facial lipoatrophy, morphological asymmetry, or debilitating scars.

BACKGROUND: Soft tissue fillers are typically used for rejuvenating an aging face; they are also employed in the treatment of certain pathologic conditions, including facial lipoatrophy, morphological asymmetry, and debilitating scars. AIMS: The aim of this clinical study was to evaluate the effectiveness and safety of Princess® Volume (PV) in patients with facial lipoatrophy (FLA), morphological asymmetry (MA), or debilitating scars (DS). PATIENTS/METHODS: This prospective, noncomparative, multicenter clinical study consisted of five visits spread across 36 weeks. Up to 60 adult patients suffering from moderate facial lipoatrophy, facial morphological asymmetry, or debilitating scars on the face were to be included. All patients were treated with an HA filler (PV). RESULTS: At Week 4, the treatment success rate in the SP was 98% (95% CI [90.4%, 100%]), as assessed by both the investigators and the patients. According to the independent reviewer, the success rate was 93% (95% CI [82.7%, 98.0%]). At Week 24, the effect was maintained in most patients, with success rates of 80% as evaluated by the investigator and 79% by the patient (95% CI [67.6%, 89.8%] and [65.6%, 88.4%], respectively). At Week 36, success rates dropped to 61% as assessed by the investigator and 59% by the patient (95% CI [46.8%, 73.5%] and [45.0%, 71.9%], respectively). CONCLUSIONS: The clinical study has proven that Princess® Volume is a safe and effective therapeutic solution for the correction of soft tissue defects in FLA and facial MA, but limited success rate to DS.

Treatment of facial lipoatrophy, morphological asymmetry, or debilitating scars with the hyaluronic acid dermal filler Princess® FILLER.

PURPOSE: The aim of this study was to evaluate the effectiveness and safety of hyaluronic acid (HA) dermal filler when used in the face for medical reconstructive purposes. PATIENTS AND METHODS: Adult patients with moderately severe facial lipoatrophy (FLA), morphological asymmetry (MA) of the face, or debilitating scars (DS) on the face were included in a prospective, noncomparative, multicenter, postmarket clinical follow-up study. All patients were treated with an HA filler (Princess® FILLER), which was injected intradermally on study Day 1, with optional touch-up 2 weeks later. The effectiveness of the treatment was evaluated at Weeks 4 and 24, using a six-grade scale ranging from "excellent" to "worsening". The assessments were conducted by both the investigator and the patient and, at Week 4, by the independent photography reviewer as well. Adverse events were collected at each visit. RESULTS: Fifty-three patients were included in the study (FLA 23, MA 17, and DS 13), and 46 patients completed a 6-month follow-up (FLA 20, MA 15, and DS 11). At Week 4 (primary endpoint), the overall treatment success rate was 100% (FLA), 100% (MA), and 94% (DS), based on assessments made by the investigator, patients, and the independent reviewer, respectively. In most patients (~95%), the effect was sustained over 6 months. Treatment-related adverse events were reported in five patients (9%) and included injection site hematoma, injection site pain, and headache. CONCLUSION: Dermal filling with HA gel is a viable treatment option for the correction of various deformities of the face resulting from FLA, MA, or DS.