The Haskins Laboratories’ pulse code modulation (PCM) system

The pulse code modulation (PCM) method of digitizing analog signals has become a standard both in digital audio and in speech research, the focus of this paper. The solutions to some problems encountered in earlier systems at Haskins Laboratories are outlined, along with general properties of A/D conversion. Specialized features of the current Haskins Laboratories system, which has also been installed at more than a dozen other laboratories, are also detailed: the Nyquist filter response, the high-frequency preemphasis filter characteristics, the dynamic range, the timing resolution for single- and (synchronized) dual-channel signals, and the form of the digitized speech files (header information, data, and label structure). While the solutions adopted in this system are not intended to be considered a standard, the design principles involved are of interest to users and creators of other PCM systems.     

Hyperactivity and attention deficits

Substantive progress has been made in our understanding of children considered hyperactive, especially in the interpersonal sphere. Evolving conceptualizations of hyperactivity and attention deficits are reviewed briefly, including changes in clinical diagnostic practices and in knowledge about developmental course. The hypothesis is advanced that the cognitive and social difficulties of hyperactive children may be better understood in terms of motivational and self-regulatory processes than as deficiencies in basic information processing. The role of stimulant medication is emphasized, both as a controversial treatment approach and as an adjunct to research on the children's problems.     

Vowel and consonant judgments are not independent when cued by the same information

Despite many attempts to define the major unit of speech perception, none has been generally accepted. In a unique study, Mermelstein (1978) claimed that consonants and vowels are the appropriate units because a single piece of information (duration, in this case) can be used for one distinction without affecting the other. In a replication, this apparent independence was found, instead, to reflect a lack of statistical power: The vowel and consonant judgments did interact. In another experiment, interdependence of two phonetic judgments was found in responses based on the fricative noise and the vocalic formants of a fricative-vowel syllable. These results show that each judgment made on speech signals must take into account other judgments that compete for information in the same signal. An account is proposed that takes segments as the primary units, with syllables imposing constraints on the shape they may take.     

Cognitive-behavioral therapies for hyperactive children: Premises,problems, and prospects

The impetus for the widespread use of CBT for children with attention deficit disorder (hyperactivity) is examined, followed by an evaluation of various facets of treatment efficacy. The many unknowns concerning treatment ingredients, targets of change, domain specificity, individual differences, palatability, and treatment-emergent side effects are then reviewed. The final section focuses on future directions, specifying some reasons for optimism despite the disappointing outcomes to date. Nontraditional uses of CBT are also proposed, including the implementation of cognitive strategies to counteract undesirable emanative effects of extant treatments and to facilitate drug discontinuance in children taking psychoactive medication.     

A tale of two negatives: differential memory modulation by threat-related facial expressions

Facial expressions serve as cues that encourage viewers to learn about their immediate environment. In studies assessing the influence of emotional cues on behavior, fearful and angry faces are often combined into one category, such as "threat-related," because they share similar emotional valence and arousal properties. However, these expressions convey different information to the viewer. Fearful faces indicate the increased probability of a threat, whereas angry expressions embody a certain and direct threat. This conceptualization predicts that a fearful face should facilitate processing of the environment to gather information to disambiguate the threat. Here, we tested whether fearful faces facilitated processing of neutral information presented in close temporal proximity to the faces. In Experiment 1, we demonstrated that, compared with neutral faces, fearful faces enhanced memory for neutral words presented in the experimental context, whereas angry faces did not. In Experiment 2, we directly compared the effects of fearful and angry faces on subsequent memory for emotional faces versus neutral words. We replicated the findings of Experiment 1 and extended them by showing that participants remembered more faces from the angry face condition relative to the fear condition, consistent with the notion that anger differs from fear in that it directs attention toward the angry individual. Because these effects cannot be attributed to differences in arousal or valence processing, we suggest they are best understood in terms of differences in the predictive information conveyed by fearful and angry facial expressions.     

ADHD treatment in the 21st century: pushing the envelope

Required for optimal intervention for attention deficit hyperactivity disorder (ADHD) is evidence-based matching of child, treatment, and situation. The landmark Multimodal Treatment Study (MTA) of Children with ADHD documented the superiority of pharmacotherapy for the vast majority of children with ADHD. Although this study could not address the problem of the match directly, it is generating important leads for research on the use of psychosocial strategies to enhance the scope and durability of treatment gains while decreasing the risks attendant upon long-term use of medication. Given the inherent distinctions between pharmacological and psychosocial treatments, conclusive answers to questions about comparative efficacy will continue to elude scientist-practitioners. Needed next is research examining ways to improve outcomes beyond the effects of medication, using systematically tailored and sequenced psychosocial approaches and exploring new treatment targets, agents, and modalities. To illustrate, some emerging findings from an ongoing experience sampling study and implications for online therapy are discussed.     

Sensitivity to Shared Information in Social Learning

Social learning has been shown to be an evolutionarily adaptive strategy, but it can be implemented via many different cognitive mechanisms. The adaptive advantage of social learning depends crucially on the ability of each learner to obtain relevant and accurate information from informants. The source of informants’ knowledge is a particularly important cue for evaluating advice from multiple informants; if the informants share the source of their information or have obtained their information from each other, then their testimony is statistically dependent and may be less reliable than testimony from informants who do not share information. In this study, we use a Bayesian model to determine how rational learners should incorporate the effects of shared information when learning from other people, conducting three experiments that examine whether human learners behave similarly. We find that people are sensitive to a number of different patterns of dependency, supporting the use of a sophisticated strategy for social learning that goes beyond copying the majority, and broadening the situations in which social learning is likely to be an adaptive strategy.     

The uncertainty of it all

The amygdala is clearly implicated in the processing of biologically relevant stimuli, particularly those that can lead to a state of fear. A new study by Herry, Bach and colleagues using both mouse and human subjects seemingly throws a wrench in the spokes by demonstrating that the amygdala is sensitive to non-biologically relevant stimuli (i.e. tones) when they occur in an unpredictable fashion. The implications of this finding for understanding the role of the amygdala in vigilance, threat assessment and anxiety are considered here.