The use of event‐related potentials in the study of early cognitive development

The article by Guillaume Thierry is a welcome one, alerting the field to the exciting ways in which event‐related potentials (ERPs) can be used to study cognitive development. It is also timely: there is great interest in the brain sciences, and in how neuroscience can be applied to cognitive development and indeed to education. In my view, however, the article is perhaps too cautious. It does not seem necessary to delay the use of ERPs in cognitive work until all in the field have agreed on the sound characterization of ERP components. It should be possible for further characterization to proceed hand‐in‐hand with data gathering on applied questions. In fact, as partly noted by Thierry, in the auditory domain well‐characterized ERP components are already available, even for infants (e.g. Cheour et al., 1997; Leppänen and Lyytinen, 1997). Furthermore, it is of developmental interest to study older children as well as infants. If ERPs are seen as a tool to complement existing behavioural investigations, rather than as a stand‐alone method to be used independently, then auditory ERPs can certainly be used in current cognitive‐developmental work. Copyright © 2005 John Wiley & Sons, Ltd.     

Pet dogs synchronize their walking pace with that of their owners in open outdoor areas

Affiliation between interacting partners is associated with a high level of behavioural synchronization in many species. Pet dogs are known to share strong affiliative bonds with their owners and to synchronize their behaviour with them when moving freely indoors. Surprisingly, outdoor dog–human interspecific synchronization has seldom been investigated. We therefore explored whether, when allowed to move freely in a familiar outdoor space, dogs synchronize their behaviour with their owners’ movements. We found that dogs visibly synchronized both their location (staying in close proximity) and their activity (moving when their owner moved, and at the same pace, and standing still when their owner stood still) with those of their owners. By demonstrating that owners act as attractors for their dogs in an outdoor space, the present study contributes new data to the understanding of interspecific behavioural synchronization.     

Before and after the vocabulary spurt: two modes of word acquisition?

This paper focuses on early lexical development, and especially the period around 18 months known as the vocabulary spurt. We first propose that this period corresponds to a shift from an associationist to a referential lexical acquisition mechanism following the developmental coupling of specific pre‐linguistic and cognitive abilities. This latter mechanism would allow the acquisition of genuine words, i.e. links between phonetically specified sound patterns and object categories. We then review the literature on early lexical acquisition by typically developing infants and infants with Down and Williams syndrome, and report some data that were recently collected on this issue. We conclude that the data so far are congruent with our proposal, but because they remain insufficient, we propose some future research that focuses on the relation between pre‐linguistic and cognitive developments.     

Evaluation of a psychosocial intervention on social support, perceived control, coping strategies, emotional distress, and quality of life of breast cancer patients

The purpose of this research was to demonstrate that a specific psychosocial intervention changes reactions to cancer and quality of life. This study was carried out on 66 patients with a first breast cancer. Patients were randomly divided into two groups: a specific intervention group (G1, 8 sessions) or a support group (G2, 8 sessions). A control group (G3) was composed of patients who refused to participate in psychological intervention. Social support, perceived control, repression of emotions, coping strategies, emotional distress, and quality of life were assessed one week before (T1) and at the end (T2) of the psychological intervention. Results showed that G1 did not have significantly modified quality of life or psychological scores. Patients of G2 had poorer emotional quality of life, use of internal causal attributions, and minimized their illness at T1 as compared to patients of G3. At Time 2 these differences were not observed.     

Transitional probabilities and positional frequency phonotactics in a hierarchical model of speech segmentation

The present study explored the influence of a new metrics of phonotactics on adults’ use of transitional probabilities to segment artificial languages. We exposed French native adults to continuous streams of trisyllabic nonsense words. High-frequency words had either high or low congruence with French phonotactics, in the sense that their syllables had either high or low positional frequency in French trisyllabic words. At test, participants heard low-frequency words and part-words, which differed in their transitional probabilities (high for words, low for part-words) but were matched for frequency and phonotactic congruency. Participants’ preference for words over part-words was found only in the high-congruence languages. These results establish that subtle phonotactic manipulations can influence adults’ use of transitional probabilities to segment speech and unambiguously demonstrate that this prior knowledge interferes directly with segmentation processes, in addition to affecting subsequent lexical decisions. Implications for a hierarchical theory of segmentation cues are discussed.     

The use of the bared-teeth display during play fighting in Tonkean macaques (Macaca tonkeana): sometimes it is all about oneself

Play signals are viewed as important means by which animals inform each other that bites, strikes, and throws that occur during play fighting are indeed playful rather than serious. One such signal is the open mouth play face that is common in primates and many other mammals. Unfortunately, as most play fighting involves biting, it can be ambiguous as to whether any instance of opening the mouth is performed to communicate playful intent or is simply a preparation for biting. In this study, open mouths co-occurring with the bared-teeth display (teeth-baring) in Tonkean macaques were used to assess the context in which facial gestures only relevant for signaling (i.e., teeth-baring is not necessary for biting) are used during play. Two predictions arising from the hypothesis that play signals are used to facilitate playful contact were tested: that the open mouth with teeth-baring should (1) be most frequent preceding contact, and (2) that it should be performed most often when bites are directed at orientations that is visible to the recipient. The data only partially support these predictions. The open mouth with teeth-baring is also frequently used when a monkey withdraws from playful contact. Moreover, it is associated with bites to body targets, such as the rump, that offer little prospect for detection by the recipient; this supports the possibility that play signals may sometimes be emitted not to communicate with the partner but with the performer itself. Thus, play signals serve multiple functions during play fighting.     

Infant ability to tell voices apart rests on language experience

A visual fixation study tested whether 7-month-olds can discriminate between different talkers. The infants were first habituated to talkers producing sentences in either a familiar or unfamiliar language, then heard test sentences from previously unheard speakers, either in the language used for habituation, or in another language. When the language at test mismatched that in habituation, infants always noticed the change. When language remained constant and only talker altered, however, infants detected the change only if the language was the native tongue. Adult listeners with a different native tongue from the infants did not reproduce the discriminability patterns shown by the infants, and infants detected neither voice nor language changes in reversed speech; both these results argue against explanation of the native-language voice discrimination in terms of acoustic properties of the stimuli. The ability to identify talkers is, like many other perceptual abilities, strongly influenced by early life experience.