Linguistic experience affects phonetic perception. However, the critical period during which experience affects perception and the mechanism responsible for these effects are unknown. This study of 6-month-old infants from two countries, the United States and Sweden, shows that exposure to a specific language in the first half year of life alters infants' phonetic perception.

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The relationship between social problem‐solving appraisals, work (organizational and incident‐related) stress and psychological distress was assessed in 78 firefighters from three divisions of a UK regional Fire Service using an anonymous self‐report questionnaire. The results of an hierarchical regression analysis indicated that work stress and problem‐solving appraisal accounted for a significant amount of the variance (49 per cent) in psychological distress scores. A small but significant amount of additional variance was accounted for by the interactions between organizational and incident‐related stress and problem‐solving appraisals. More specific analysis indicated that of the six problem‐solving appraisal dimensions, the approach factor was the only significant predictor of psychological distress, after work stress levels were controlled. Individuals in different fire service ranks reported similar levels of organizational stress, self‐appraised problem solving and psychological distress, although watch members had higher incident‐related stress levels than senior officers. There were also differences in the pattern of organizational and incident‐related stressors between fire service ranks. Results are discussed in terms of the influence of problem‐solving appraisals on work stress and psychological distress, and the potential importance of such appraisals in intervention strategies for stress management in the fire service. Copyright © 2001 John Wiley & Sons, Ltd.

Previous studies of infants’ babbling have reported contradictory results as to the extent and timing of discernible phonetic influences of the ambient language. In the present experiment, five experienced phoneticians were asked to listen for ambient language effects on vocalizations produced by American and Swedish 12- and 18-month-olds (with 8 children in each language and age group), and to motivate their decisions in terms of word or phonetic cue perception. Group results indicated that listeners did not perceive effects of ambient language on pure babbles for either of the two age groups, whereas a clear effect appeared in both age groups given a more liberal definition of babbling. This is taken to suggest that results of ambient language listening tests may depend crucially on judgments of vocalizations’ word status. As compared to the group trends, listener responses to individual children’s vocalizations did not indicate that a majority of either 12- or 18-monthers were sufficiently native-sounding to be reliably identified on the basis of ambient language. A closer analysis of listeners’ use of phonetic cues indicated that one single phonetic property, the grave tonal word accent, was discerned by most listeners in vocalizations produced by the Swedish 18-monthers; this property was also discerned by one listener in vocalizations produced by Swedish 12-monthers. This result is consistent with the generally held belief in the primacy of tonal features in phonetic acquisition, and with experimental evidence indicating that Swedish mothers tend to enhance word accent contours in baby talk. In the final section of the paper, the results are discussed with a view to reconcile competing theories of babbling development, notably the ‘babbling drift’ and the ‘independence’ hypotheses.