Effect of interaction type on the characteristics of pet-directed speech in female dog owners

Recent studies focusing on the interspecific communicative interactions between humans and dogs show that owners use a special speech register when addressing their dog. This register, called pet-directed speech (PDS), has prosodic and syntactic features similar to that of infant-directed speech (IDS). While IDS prosody is known to vary according to the context of the communication with babies, we still know little about the way owners adjust acoustic and verbal PDS features according to the type of interaction with their dog. The aim of the study was therefore to explore whether the characteristics of women’s speech depend on the nature of interaction with their dog. We recorded 34 adult women interacting with their dog in four conditions: before a brief separation, after reuniting, during play and while giving commands. Our results show that before separation women used a low pitch, few modulations, high intensity variations and very few affective sentences. In contrast, the reunion interactions were characterized by a very high pitch, few imperatives and a high frequency of affectionate nicknames. During play, women used mainly questions and attention-getting devices. Finally when commanding, women mainly used imperatives as well as attention-getting devices. Thus, like mothers using IDS, female owners adapt the verbal as well as the non-verbal characteristics of their PDS to the nature of the interaction with their dog, suggesting that the intended function of these vocal utterances remains to provide dogs with information about their intentions and emotions.     

Holistic processing and reliance on global viewing strategies in older adults' face perception

There is increasing evidence that face recognition might be impaired in older adults, but it is unclear whether the impairment is truly perceptual, and face specific. In order to address this question we compared performance in same/different matching tasks with face and non-face objects (watches) among young (mean age 23.7) and older adults (mean age 70.4) using a context congruency paradigm (Meinhardt-Injac, Persike & Meinhardt, 2010, Meinhardt-Injac, Persike and Meinhardt, 2011a). Older adults were less accurate than young adults with both object classes, while face matching was notably impaired. Effects of context congruency and inversion, measured as the hallmarks of holistic processing, were equally strong in both age groups, and were found only for faces, but not for watches. The face specific decline in older adults revealed deficits in handling internal facial features, while young adults matched external and internal features equally well. Comparison with non-face stimuli showed that this decline was face specific, and did not concern processing of object features in general. Taken together, the results indicate no age-related decline in the capabilities to process faces holistically. Rather, strong holistic effects, combined with a loss of precision in handling internal features indicate that older adults rely on global viewing strategies for faces. At the same time, access to the exact properties of inner face details becomes restricted.     

Stress sensitive healthy females show less left amygdala activation in response to withdrawal-related visual stimuli under passive viewing conditions

The amygdalae are key players in the processing of a variety of emotional stimuli. Especially aversive visual stimuli have been reported to attract attention and activate the amygdalae. However, as it has been argued that passively viewing withdrawal-related images could attenuate instead of activate amygdalae neuronal responses, its role under passive viewing conditions remains unclear. Furthermore, because individual sensitivity to stress reactions has been shown to modulate amygdalae processing, the aim of the current event-related fMRI study was to investigate whether individual differences in stress proneness could influence amygdala responses while passively viewing withdrawal and approach-related visual images. We presented 14 healthy female subjects with a random sequence of images of happy 'healthy' baby faces (approach-related) and baby faces disfigured by severe dermatological conditions (withdrawal-related). No instructions were given other than to watch the images attentively. We integrated individual perceived stress (PSS) scores in our analysis. The processing of withdrawal-related pictures resulted in less left amygdala activity in females scoring higher on perceived stress. Our findings suggest that stress-sensitive healthy females are less able to fully attend to withdrawal-related visual material and in essence avoid exposure to such images in an effort to reduce strong psychophysiological responses. Although the relatively small number of participants limits drawing firm conclusions, we suggest that in passive viewing emotional brain imaging paradigms, individual information on stress proneness should be included in the interpretation of amygdala neuronal processes.