Perception of size-related formant information in male koalas (Phascolarctos cinereus)

Advances in bioacoustics allow us to study the perceptual and functional relevance of individual acoustic parameters. Here, we use re-synthesised male koala bellows and a habituation-dishabituation paradigm to test the hypothesis that male koalas are sensitive to shifts in formant frequencies corresponding to the natural variation in body size between a large and small adult male. We found that males habituated to bellows, in which the formants had been shifted to simulate a large or small male displayed a significant increase in behavioural response (dishabituation) when they were presented with bellows simulating the alternate size variant. The rehabituation control, in which the behavioural response levels returned to that of the last playbacks of the habituation phase, indicates that this was not a chance increase in response levels. Our results provide clear evidence that male koalas perceive and attend to size-related formant information in their own species-specific vocalisations and suggest that formant perception is a widespread ability shared by marsupials and placental mammals, and perhaps by vertebrates more widely.     

Phonological perception by birds: budgerigars can perceive lexical stress

Metrical phonology is the perceptual “strength” in language of some syllables relative to others. The ability to perceive lexical stress is important, as it can help a listener segment speech and distinguish the meaning of words and sentences. Despite this importance, there has been little comparative work on the perception of lexical stress across species. We used a go/no-go operant paradigm to train human participants and budgerigars (Melopsittacus undulatus) to distinguish trochaic (stress-initial) from iambic (stress-final) two-syllable nonsense words. Once participants learned the task, we presented both novel nonsense words, and familiar nonsense words that had certain cues removed (e.g., pitch, duration, loudness, or vowel quality) to determine which cues were most important in stress perception. Members of both species learned the task and were then able to generalize to novel exemplars, showing categorical learning rather than rote memorization. Tests using reduced stimuli showed that humans could identify stress patterns with amplitude and pitch alone, but not with only duration or vowel quality. Budgerigars required more than one cue to be present and had trouble if vowel quality or amplitude were missing as cues. The results suggest that stress patterns in human speech can be decoded by other species. Further comparative stress-perception research with more species could help to determine what species characteristics predict this ability. In addition, tests with a variety of stimuli could help to determine how much this ability depends on general pattern learning processes versus vocalization-specific cues.     

Gender Differences in Reactions to Mental Illness Labeling: The Role of Agency and Communion

Numerous individual characteristics influence responses to receiving a mental health diagnosis, including gender. This study sought to determine how gender influences reactions to being labeled as depressed or not depressed, which were categorized as falling into themes of communion or agency. Using the themes developed by Niedzwienska (2003), 168 college students’ responses to depression labels were coded as a part of a laboratory experiment. The results indicate that the expected sex differences do exist, but multivariate analyses indicate that the choice of communal themes was influenced by sex but the use of agency themes was not influenced by sex.     

Family burden of compulsive hoarding: results of an internet survey

Compulsive hoarding, the acquisition of and failure to discard large numbers of possessions, is associated with substantial health risk, impairment in functioning, and economic burden. Despite clear indications that hoarding has a detrimental effect on people living with or near someone with a hoarding problem, no empirical research has examined these harmful effects. The aim of the present study was to examine the burden of hoarding on family members. Six hundred sixty-five family informants who reported having a family member or friend with hoarding behaviors completed an internet-based survey. Living with an individual who hoards during childhood was associated with elevated reports of childhood distress and family strain. Family members reported high levels of patient rejection attitudes, suggesting high levels of family frustration and hostility. Rejecting attitudes were predicted by severity of hoarding symptoms, the individual's perceived lack of insight into the behavior, and having lived in a cluttered environment during childhood. These results suggest that compulsive hoarding adversely impacts not only the hoarding individual, but also those living with them.     

Learning and memory deficits upon TAU accumulation in Drosophila mushroom body neurons

Mutations in the neuronal-specific microtubule-binding protein TAU are associated with several dementias and neurodegenerative diseases. However, the effects of elevated TAU accumulation on behavioral plasticity are unknown. We report that directed expression of wild-type vertebrate and Drosophila TAU in adult mushroom body neurons, centers for olfactory learning and memory in Drosophila, strongly compromised associative olfactory learning and memory, but olfactory conditioning-relevant osmotactic and mechanosensory responses remained intact. In addition, TAU accumulation in mushroom body neurons did not result in detectable neurodegeneration or premature death. Therefore, TAU-mediated structural or functional perturbation of the microtubular cytoskeleton in mushroom body neurons is likely causal of the behavioral deficit. These results indicate that behavioral plasticity decrements may be the earliest detectable manifestations of tauopathies.     

Eye preferences in captive chimpanzees

Over the last century, the issue of brain lateralization in primates has been extensively investigated and debated, yet no previous study has reported eye preference in great apes. This study examined eye preference in 45 captive chimpanzees (Pan troglodytes) in response to various stimuli. Eye preference was assessed when animals looked through a hole that only accommodated one eye at an empty box, a mirror, a picture of a dog, a rubber snake, food biscuits, bananas, a rubber duck, and a video camera. Main effects of stimulus type were found for direction of eye preference, number of looks, and looking duration, but not for strength of eye preference. A left-eye bias was found for viewing the rubber snake and a right-eye bias was found for viewing the bananas, supporting theories that emotional valence may affect lateralized behaviors. In addition, a significant shift in eye preference took place from the initial look to subsequent looks when viewing the snake. These results are not consistent with previous reports of human eye preference and may reflect lateralization differences for emotional processing. No relationship between eye preference and previously recorded hand preference was found.