Degrees of freedom and motor planning in purposive movement

This paper presents empirical evidence suggesting that healthy humans can perform a two degree of freedom visuo-motor pursuit tracking task with the same response time delay as a one degree of freedom task. In contrast, the time delay of the response is influenced markedly by the nature of the motor synergy required to produce it. We suggest a conceptual account of this evidence based on adaptive model theory, which combines theories of intermittency from psychology and adaptive optimal control from engineering. The intermittent response planning stage has a fixed period. It possesses multiple optimal trajectory generators such that multiple degrees of freedom can be planned concurrently, without requiring an increase in the planning period. In tasks which require unfamiliar motor synergies, or are deemed to be incompatible, internal adaptive models representing movement dynamics are inaccurate. This means that the actual response which is produced will deviate from the one which is planned. For a given target-response discrepancy, corrective response trajectories of longer duration are planned, consistent with the principle of speed-accuracy trade-off. Compared to familiar or compatible tasks, this results in a longer response time delay and reduced accuracy. From the standpoint of the intermittency approach, the findings of this study help make possible a more integral and predictive account of purposive action.     

Conflict Intensity,Family History,and Physiological Stress Reactions to Conflict Within Romantic Relationships

This study drew upon the physiological model of stress and desensitization processes to deduce hypotheses linking the intensity of conflict communication and exposure to familial verbal aggression in childhood to experiences of conflict within romantic relationships. One hundred college‐aged students (50 dating couples) participated in a dyadic interaction in which partners discussed a source of conflict in their romantic relationship. Participants reported childhood exposure to familial verbal aggression, third‐party observers rated the intensity of conflict communication, and salivary cortisol indexed physiological stress responses to the conflict interactions. As predicted, results showed a positive association between conflict intensity and cortisol reactivity, and this association was attenuated for individuals who reported higher, rather than lower, levels of childhood exposure to familial verbal aggression.     

Quantifying Intervention Intensity: A Systematic Approach to Evaluating Student Response to Increasing Intervention Frequency

Response to intervention (RTI) has been discussed as a new model of assessment. Although the basic process by which RTI works has received frequent attention in the literature, the available research leaves several important questions unanswered (Kavale et al. in Learn Disabil Q 28(1): 2–16, 2005). One concept within RTI that has received little empirical consideration is intervention intensity. The purpose of this study was to evaluate the impact of the application of increased intervention frequency on the mathematics performance of students and to evaluate this increased frequency as a systematic means of increasing and quantifying intervention strength. Results indicate that although all students were responsive to the intervention, some participants were sensitive only to more frequent application of the treatment or at more intense levels of treatment. Through this methodology a means of quantifying treatment intensity was also identified and implications for future research are discussed.     

The attentional blink reveals sluggish attentional shifting in adolescents with specific language impairment

Rapid processing deficits have been the subject of much debate in the literature on specific language impairment (SLI). Hari and Renvall (2001) [Hari, R. & Renvall, H. (2001). Impaired processing of rapid stimulus sequences in dyslexia. Trends in cognitive sciences, 5, 525-532.] proposed that the source of this deficit can be attributed to sluggish attentional shifting abilities. That is, more time is required to shift attention between stimuli. To test this claim, 26 adolescents with SLI (divided into two subgroups to control for differences in non-verbal intelligence) and 14 controls were presented with a rapid serial visual presentation task. In this task participants were asked to detect two visual targets presented serially with distracter items with varying inter-target intervals (i.e., time difference between targets). This task was designed to elicit an attentional blink (AB). The AB describes the phenomenon whereby non-impaired individuals are less likely to report the second of two targets presented within 200-500ms of each other. After controlling for group differences in non-verbal intelligence, the SLI group was found to be significantly less accurate than the control group at successfully reporting the second target at inter-target intervals of 100, 200, 300, 400 and 800ms. The results were interpreted to suggest that adolescents with language impairments have an AB which differs from non-impaired individuals in both magnitude and duration.     

Integrity Testing, Personality, and Design: Interpreting the Personnel Reaction Blank

Companies and organizations use integrity tests to screen job applicants, and the fakability of these tests remains a concern. The present study uses two separate designs to analyze the fakability of the Personnel Reaction Blank (PRB) and the personality constructs related to integrity test scores. The results demonstrate that the PRB can be successfully faked. Moreover, a within-participants design resulted in significantly greater faking than the between-participants design. The personality constructs conscientiousness, agreeableness, and neuroticism were significantly correlated with honest scores on the PRB, and there was a significant negative correlation between conscientiousness and magnitude of faking.

Perceptual,affective, and cognitive judgments of odors: pleasantness and handedness effects

The present study sought to examine the differential processing of pleasant, neutral, and unpleasant odors. The effects of the nostril stimulated (left or right) and the type of judgment (perceptual, affective, or cognitive) performed on the olfactory stimuli were also studied. To this end, 64 subjects were asked to smell pleasant, neutral, and unpleasant odors under four conditions (detection, intensity, pleasantness, and familiarity tasks). The participants were to perform these tasks as quickly as possible, while response times were recorded. The results showed that (i) unpleasant odors were assessed more rapidly than neutral or pleasant odors, and that this was specifically true (ii) during right nostril stimulation, and (iii) during pleasantness assessment, suggesting possible differential cerebral hemisphere involvement, with a right-side advantage for processing of unpleasant affect in olfaction. A handedness effect on familiarity judgment is also discussed.     

Core beliefs,automatic thoughts and response expectancies in predicting public speaking anxiety

The present study examined the relationships between broad core cognitions, situation-specific automatic thoughts, and response expectancies in regard to their relative contributions to public speaking anxiety. Ninety-nine socially anxious participants (mean age = 20.25) completed measures of irrational beliefs and automatic thoughts specific to public speaking. Participants were then announced the task – giving a speech in front of a virtual reality audience – and response expectancies were measured. Subjective anxiety was measured just before the speech. As predicted, response expectancies and negative automatic thoughts specific to public speaking were each found to mediate the relationship between irrational beliefs and public speaking anxiety. Multiple mediation analysis indicated that the core irrational beliefs generated specific beliefs (i.e., response expectancies that primed automatic thoughts) that acted on speech-related anxiety.     

Circuits and circumstances: the neurobiological consequences of early relationship experiences and how they shape later behaviour

The last decade has seen a vast increase in knowledge of how the human brain develops. It has been demonstrated that both the establishment of synaptic connections between neurones and the programming of neurochemical responses that have an effect on the whole body are dependent on experience. The most sensitive period for brain growth, the time of optimal plasticity, is over the first two or three years of life. If the baby's neurological development is threatened by abuse or neglect, which includes excessive attachment disruption, the damage may set its stamp on the rest of life.     

Sequence-sensitive exemplar and decision-bound accounts of speeded-classification performance in a modified Garner-tasks paradigm

Among the most fundamental results in the area of perceptual classification are the “correlated facilitation” and “filtering interference” effects observed in Garner’s (1974) speeded categorization tasks: In the case of integral-dimension stimuli, relative to a control task, single-dimension classification is faster when there is correlated variation along a second dimension, but slower when there is orthogonal variation that cannot be filtered out (e.g., by attention). These fundamental effects may result from participants’ use of a trial-by-trial bypass strategy in the control and correlated tasks: The observer changes the previous category response whenever the stimulus changes, and maintains responses if the stimulus repeats. Here we conduct modified versions of the Garner tasks that eliminate the availability of a pure bypass strategy. The fundamental facilitation and interference effects remain, but are still largely explainable in terms of pronounced sequential effects in all tasks. We develop sequence-sensitive versions of exemplar-retrieval and decision-bound models aimed at capturing the detailed, trial-by-trial response-time distribution data. The models combine assumptions involving: (i) strengthened perceptual/memory representations of stimuli that repeat across consecutive trials, and (ii) a bias to change category responses on trials in which the stimulus changes. These models can predict our observed effects and provide a more complete account of the underlying bases of performance in our modified Garner tasks.     

The Attention-Lapse and Motor Decoupling accounts of SART performance are not mutually exclusive

There is an ongoing debate about the mechanisms purported to underlie performance in the Sustained-Attention-to-Response Task (SART). Whereas the Attention-Lapse account posits that SART errors result from attentional disengagement, the Motor Decoupling account proposes that SART errors result from failures to inhibit a fast, prepotent motor response, despite adequate attention to the task. That SART performance might be fully accounted for by motor decoupling is problematic for a Attention-Lapse account, and for the use of the SART as an index of attention lapses. To test whether SART performance is in fact fully accounted for by motor decoupling, I examined the relation between SART performance and attention lapses while controlling for motor decoupling. The results were clear: The SART was associated with attention lapses independently of motor decoupling. Thus, the present study suggests that both accounts are correct and that the SART is a valid measure of attention lapses.