A dynamical approach to speech categorization: Two routes to learning

Learning to perceive a non-native speech sound reliably is a specific instance of the more general issue of category learning. Here we take a dynamical approach that provides a theoretically motivated way to understand individual differences in the process of learning to perceive new speech sounds. Fundamental to this approach is the focus on the initial categorization and discrimination abilities of individual perceivers and how these structure the form of learning over time. Two distinct patterns of learning were observed that were predictable based on initial perceptual abilities. In one pattern, subjects became more attuned to small acoustic distinctions between stimuli and could use that sensitivity to label tokens reliably. In the second pattern, subjects became less attuned to within-category acoustic distinctions, suggesting cognitive restructuring. Finally, we present a dynamical model that incorporates both modes of category learning, and also allows for failure to learn.     

An efficient computerized testing method for the capuchin monkey (<Emphasis Type="Italic">Cebus apella</Emphasis>): Adaptation of the LRC-CTS to a socially housed nonhuman primate species

Even with advances in automated testing techniques, the capuchin monkey (Cebus apella) can be a difficult species to test in the laboratory, given its social/behavioral tendencies and typical activity pattern. Laboratories that maintain social colonies of capuchin monkeys are able to separate and test individuals, but the process can be very effortful and time consuming, and the resulting data can be modest in quantity. The present article describes procedures and apparatuses that were used to train a colony of computer-naive capuchin monkeys to quickly and reliably isolate themselves from group members and interact with a computerized test system in order to produce a large volume of data. Several elements that were important in motivating the monkeys to participate are discussed.     

Maternal perceptions of the sleep patterns of premature infants at seven months corrected age compared to full-term infants

It has been reported that 83%–87% of full-term infants regularly sleep through the night (from midnight to 5 a.m.) by 6 months of age, but there is little information about the sleep patterns of premature infants. The purpose of the current study was to identify maternal perceptions of the sleep patterns of premature infants. Parents of 32 premature infants with birth weight below 1,750 gm and of 13 full-term infants completed a 24-hour sleep record in 30-minute epochs for 1 week at 7 months of chronological (term) or corrected age (premature). Mean birth weight of premature infants was 1,278 ± 340 gm, with a gestational age of 30.4 ± 2.7 weeks. The daily total sleep time, longest sleep segment, frequency of sleep-wake transitions, and percentage of night sleep (8 p.m.–8 a.m.), averaged from the 1-week sleep record and number of night wakenings per week, were used as indicators of sleep patterns. The longest reported sleep segments of premature infants were significantly shorter than those of full-term infants (8.2 ± 2 hours versus 9.6 ± 1 hour, p < 0.01) and the number of night wakenings per week was significantly greater (3.13 ± 3 versus 0.54 ± 7, p < 0.005). Total reported sleep time, percentage of night sleep, and sleep-wake transitions did not differ significantly between premature and full-term infants. However, analysis of feeding events revealed that premature infants received significantly more feedings between midnight and 5 a.m. (M = 0.31 + 3 versus M = 0.06 + 1, p < 0.001). We conclude that sleep pattern diaries kept by parents indicate that premature infants have developed a diurnal sleep rhythm by 7 months corrected age, but they still have shorter sleep segments and they awaken more during the night than term infants.     

A postpartum telephone program of reassurance,information, and early intervention in a family practice

This paper presents a program developed in a family practice office to provide reassurance, guidance, and early detection and intervention for mothers and their new infants in the first month of the infant's life. Telephone calls from an office nurse at 2 weeks of age followed by a written questionnaire demonstrated a dichotomy between the mothers' expressions of their physical and emotional problems. Feeding was the most prominently expressed concern, but we also found that complaints or worries about feeding were also an acceptable way to initiate intervention for more serious problems.     

How Groups Merge: The Effects of Merger Integration Patterns on Anticipated Commitment to the Merged Organization1

This study examined the influence of merger integration patterns on expectations about the merger process. The integration patterns included the absorb, in which the merged organization closely resembled the acquiring company; the blend, in which features of both companies were maintained, and the combine, in which the organization resembled neither pre-merger company. Undergraduates role-played employees of a merging organization and written scenarios manipulated the integration pattern and membership in the acquired or acquiring organization. Participants' commitment to the merged organization was most favorable in the combine pattern. Path analyses indicated that the relationship between merger integration pattern and organizational commitment is mediated by the conditions of intergroup contact, perceptions of organizational support, organizational unity, and the degree of threat experienced.     

Categorization of Ambiguous Sentences as a Function of a Changing Prosodic Parameter: A Dynamical Approach

The present study investigates the dynamics of changes in interpretation of ambiguous sentences. The sentences used had alternative interpretations with different surface structures (bracketing). Continua were created by systematic manipulation of prosodic cues (relative foot duration), resulting in stimulus sentences that spanned the range between the two interpretations. Continua were presented to subjects who were requested to indicate as quickly as possible which meaning they perceived. The pattern of responses and response times revealed the presence of hysteresis. That is, when the values of prosodic parameters are congruent with both interpretations, the individual's recent history decides which meaning will be perceived. Thus, we can treat this categorization process as a transition from an initially stable meaning that loses stability with variations in prosody (our control parameter). The same underlying dynamics have been observed in studies of perception of syllables and aspects of visual perception. Apart from demonstrating the same characteristics of pattern formation at various levels of cognition, the study points to the usefulness of the dynamical approach in the investigation of language understanding.