Developmental-behavioral initiation of evolutionary change

The traditional approach to evolutionary psychology relies entirely on natural selection as the cause of the evolution of adaptations. Exclusive reliance on natural selection overlooks the fact that changes in development are a necessary prerequisite for evolutionary change. These developmental changes provide the material for natural selection to work on. In the neo-Darwinian scenario, the mechanisms of evolution are mutation or genetic recombination, selection, migration, and eventual reproductive isolation. In the spirit of evolutionary pluralism, the author describes a different 3-stage scenario in which migration (the invasion of new niches or habitats) may occur without mutation or genetic recombination and selection first initiating a change in genes or gene frequencies.     

The Cross-Modal Coordination of Interpersonal Timing: Six-Week-Olds Infants' Gaze with Adults' Vocal Behavior

The purpose of this study was to examine the hypothesis that 6-week-old infants are capable of coordinated interpersonal timing within social interactions. Coordinated interpersonal timing refers to changes in the timing of one individual's behavior as a function of the timing of another individual's behavior. Each of 45, first-born 6-week-old infants interacted with his or her mother and a stranger for a total of 14 minutes. The interactions were videotaped and coded for the gaze behavior of the infants and the vocal behavior of the mothers and strangers. Time-series regression analyses were used to assess the extent to which the timing of each of the infants' gazes was coordinated with the timing of the adults' vocal behavior. The results revealed that (a) coordinated timing occurs between infants and their mothers and between infants and strangers as early as when infants are 6 weeks old, and (b) strangers coordinated the timing of their pauses with the infants to a greater extent than did mothers. The findings are discussed in terms of the role of temporal sensitivity in social interaction.     

Nonspatial attentional shifts between audition and vision

This study investigated nonspatial shifts of attention between visual and auditory modalities. The authors provide evidence that the modality of a stimulus (S1) affected the processing of a subsequent stimulus (S2) depending on whether they shared the same modality. For both vision and audition, the onset of S1 summoned attention exogenously to its modality, causing a delay in processing S2 in a different modality. That undermines the notion that auditory stimuli have a stronger and more automatic alerting effect than visual stimuli (M. I. Posner, M. J. Nissen, & R. M. Klein, 1976). The results are consistent with other recent studies showing cross-modal attentional limitation. The authors suggest that such cross-modal limitation can be produced by simply presenting S1 and S2 in different modalities and that central processing mechanisms are also, at least partially, modality dependent.     

Bigger than a breadbox? Attention to distractors may not enhance negative priming

In several recent studies, P. A. MacDonald and colleagues (e.g., P. A. MacDonald & S. Joordens, 2000) reported unusually large negative priming effects and claimed that attention to distractors, counter to expectations, served to enhance the magnitude of the effect. In 3 experiments using their novel comparative judgment task, negative priming was assessed using both a control condition based on that of P. A. MacDonald, S. Joordens, and K. N. Seergobin (1999) and one in which control probe items exactly matched those on ignored repetition trials. In MacDonald et al.'s unmatched control condition, participants were faster than on ignored repetition trials, but this difference was reduced or absent when control items were matched. This result led to the conclusion that the apparently large negative priming effect reported by MacDonald and colleagues may be an artifact arising because judgments for a subset of their control trials were relatively easier than for ignored repetition trials.     

Speech treatment and support group experiences of people who participate in the National Stuttering Association

Support groups are rapidly becoming an important part of the recovery process for many people who stutter, and a growing number of speech-language pathologists (SLPs) are encouraging their clients to participate in support groups. At present, however, little is known about the individuals who join stuttering support groups and the benefits they derive from their participation. This study surveyed members of the National Stuttering Association (NSA) to learn about their experiences in support groups, as well as their experiences in speech therapy. Respondents were 71 people who attended the 1999 NSA conference in Tacoma, WA. The majority of respondents had participated in treatment several times during their lives, using a variety of techniques. Respondents who had participated in fluency-shaping treatments were more likely to report that they had experienced a relapse than those who had participated in stuttering modification or combined treatments. Also, there was a strong positive correlation between respondents' satisfaction with treatment and their judgments of clinicians' competence, suggesting that improved training for SLPs should lead to improved treatment for people who stutter. Results will be used to provide a foundation for further evaluations of the benefits of support group participation for people who stutter. EDUCATIONAL OBJECTIVES: The reader will learn (a) that many people who participate in the NSA have had numerous and varied experiences with speech treatment throughout their lives, (b) which aspects of treatment and support group participation are seen as most beneficial for people who participate in the NSA.     

The motivating function of thinking about the future: expectations versus fantasies

Two forms of thinking about the future are distinguished: expectations versus fantasies. Positive expectations (judging a desired future as likely) predicted high effort and successful performance, but the reverse was true for positive fantasies (experiencing one's thoughts and mental images about a desired future positively). Participants were graduates looking for a job (Study 1), students with a crush on a peer of the opposite sex (Study 2), undergraduates anticipating an exam (Study 3), and patients undergoing hip-replacement surgery (Study 4). Effort and performance were measured weeks or months (up to 2 years) after expectations and fantasies had been assessed. Implications for the self-regulation of effort and performance are discussed.     

The police officer's dilemma: using ethnicity to disambiguate potentially threatening individuals

Using a simple videogame, the effect of ethnicity on shoot/don't shoot decisions was examined. African American or White targets, holding guns or other objects, appeared in complex backgrounds. Participants were told to "shoot" armed targets and to "not shoot" unarmed targets. In Study 1, White participants made the correct decision to shoot an armed target more quickly if the target was African American than if he was White, but decided to "not shoot" an unarmed target more quickly if he was White. Study 2 used a shorter time window, forcing this effect into error rates. Study 3 replicated Study 1's effects and showed that the magnitude of bias varied with perceptions of the cultural stereotype and with levels of contact, but not with personal racial prejudice. Study 4 revealed equivalent levels of bias among both African American and White participants in a community sample. Implications and potential underlying mechanisms are discussed.     

On the role of visual afferent information for the control of aiming movements toward targets of different sizes

The authors investigated (a). whether the specificity of practice hypothesis is mediated by the importance of visual afferent information for the control of manual aiming movements and (b). how movement planning and online correction processes to the movement initial impulse are affected by the withdrawal of visual information in transfer. In acquisition, participants (N = 40) aimed at targets of different sizes in a full-vision or in a target-only condition before being transferred to a target-only condition without knowledge of results. The results supported the hypothesis that learning is specific to the source or sources of afferent information that are more likely to ensure optimal performance. The results also suggested that individuals will not always use visual afferent information more extensively when aiming at a small rather than at a large target. Instead, in a temporally constrained task, the relative efficiency of visually based corrections appears to mediate how exclusively an individual will rely on online visual afferent information for movement control. Finally, the detailed kinematic analysis performed in the present study clearly indicated that online modifications to the movement primary impulse are possible, arguing for a continuous or pseudo-continuous control of relatively slow aiming movements on the basis of visual afferent input.     

Response styles in affect ratings: making a mountain out of a molehill

Ratings of affect words are the most commonly used method to assess pleasant affect (PA) and unpleasant affect (UA). The reliance on self-reports would be problematic if affect ratings were heavily influenced by response styles. Several recent publications have indeed suggested (a) that the influence of response styles on affect ratings is pervasive, (b) that this influence can be controlled by variations of the response format using multitrait-multimethod models, and (c) the discriminant validity of PA and UA is spurious. In this article, we examined the evidence for these claims. We demonstrate that (a) response styles have a negligible effect on affect ratings, (b) multiple response formats produce the same results as a single response format, and (c) the discriminant validity of PA and UA is not a method artifact. Rather, evidence against discriminant validity is due to the use of inappropriate response formats that respondents interpreted as bipolar scales.