Dissociation of explicit and implicit timing in repetitive tapping and drawing movements

Four experiments explored the hypothesis that temporal processes may be represented and controlled explicitly or implicitly. Tasks hypothesized to require explicit timing were duration discrimination, tapping, and intermittent circle drawing. In contrast, it was hypothesized that timing control during continuous circle drawing does not rely on an explicit temporal representation; rather, temporal control is an emergent property of other control processes (i.e., timing is controlled implicitly). Temporal consistency on the tapping and intermittent drawing tasks was related, and performance on both of these tasks was correlated with temporal acuity on an auditory duration discrimination task. However, timing variability of these 3 tasks was not correlated with timing variability of continuous circle drawing. These results support the hypothesized distinction between explicit and implicit temporal representations.     

The fit and implementation of sexual harassment law to workplace evaluations

Three studies used videotaped harassment complaints to examine the impact of legal standards on the evaluation of social-sexual conduct at work. Study 1 demonstrated that without legal instructions, college students' judgment strategies were highly variable. Study 2 compared 2 current legal standards, the "severity or pervasiveness test" and a proposed utilitarian alternative (i.e., the rational woman approach). Undergraduate participants taking the perspective of the complainant were more sensitive to offensive conduct than were those adopting an objective perspective. Although the utilitarian altemative further increased sensitivity on some measures, it failed to produce a principled judgment strategy. Finally, Study 3 examined the kinds of errors that full-time workers make when applying the "severity or pervasiveness" test to examine more closely the sensitivity of the subjective approach.     

Programming of endogenous and exogenous saccades: evidence for a competitive integration model

Participants were required to make a saccade to a uniquely colored target while ignoring the presentation of an onset distractor. The results provide evidence for a competitive integration model of saccade programming that assumes endogenous and exogenous saccades are programmed in a common saccade map. The model incorporates a lateral interaction structure in which saccade-related activation at a specific location spreads to neighboring locations but inhibits distant locations. In addition, there is top-down, location-specific inhibition of locations to which the saccade should not go. The time course of exogenous and endogenous activation in the saccade map can explain a variety of eye movement data, including endpoints, latencies, and trajectories of saccades and the well-known global effect.     

Understanding the relations among gender,disinhibition, and disruptive behavior in adolescents

This study examined whether disinhibition shows similar relations with attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD) symptomatology among male and female adolescents. The mixed-incentive or punishment condition of Newman's go/no-go task was administered to 172 adolescents. As expected, ADHD symptoms in boys and girls were predictive of disinhibition (i.e., commission errors) in the mixed-incentive but not punishment condition. Also consistent with expectations, CD symptoms in boys were predictive of disinhibition in the mixed-incentive but not punishment condition. In contrast, CD symptoms in girls were not predictive of disinhibition in either condition. These findings are discussed in terms of implications for understanding sex differences in the etiology of ADHD and CD.     

A longitudinal study of pain sensitivity and blood pressure in adolescent boys: results from a 5-year follow-up.

A growing literature has observed a significant reduction in pain sensitivity among hypertensive animals and humans. It is uncertain whether a reduced sensitivity to pain can be observed in nonnotensive individuals who go on to develop high blood pressure. Blood pressure (BP) was reassessed in one hundred fifteen 19-year-old boys initially tested at age 14, when they were also presented with a pain stimulus (mechanical finger pressure). Hierarchical regression analyses indicated that information regarding pain tolerance improved prediction of changes in systolic and diastolic blood pressure beyond that afforded by differences in BP at age 14, parental history of hypertension, and body mass index. These analyses suggest that pain sensitivity may be associated with physiological processes involved in the development of sustained high blood pressure.     

Mechanisms of source confusion and discounting in short-term priming 2: effects of prime similarity and target duration

D. E. Huber, R. M. Shiffrin, K. B. Lyle, and K. I. Ruys (2001) tested two-alternative, forced-choice (2-AFC) perceptual identification in a short-term priming task. For repetition priming, passive viewing of primes resulted in a preference to choose repeated words, but actively responding to primes resulted in a preference against choosing repeated words. These results were explained with a computational model, responding optimally with unknown sources of evidence (ROUSE), using the offsetting mechanisms of source confusion and discounting. An analysis of ROUSE revealed conditions under which discounting efficacy should diminish, causing a preference for primed words even with active prime processing. Two new studies confirm 2 such conditions: very short target flash durations and very low similarity between primes and primed choice words. These a priori predictions contrast with the a posteriori data fits of a multinomial model developed by R. Ratcliff and G. McKoon (2001).     

Object-based selection within and beyond the focus of spatial attention

In a series of experiments, we examined the effect of perceptual objects on visual attentional processing in the presence of spatially cued attentional selection. Subjects made speeded judgments about two visual elements that were either both on the same object or on two different objects. Judgments were faster when the elements were on the same object than when they were on different objects, revealing an object advantage. Importantly, the object advantage remained even when either exogenous or endogenous spatial cues were used to direct the subjects' attention to a part of the display, contrary to earlier findings of other researchers. The object advantage, however, did disappear when the stimulus duration was shortened substantially. The results show that object-based selection is pervasive and is not diminished by the act of selective attention. The results are discussed in terms of their implications for the mechanisms that underlie attentional selection.     

A computational account of altered error processing in older age: Dopamine and the error-related negativity

When participants commit errors or receive feedback signaling that they have made an error, a negative brain potential is elicited. According to Holroyd and Coles’s (in press) neurocomputational model of error processing, this error-related negativity (ERN) is elicited when the brain first detects that the consequences of an action are worse than expected. To study age-related changes in error processing, we obtained performance and ERN measures of younger and high-functioning older adults. Experiment 1 demonstrated reduced ERN amplitudes in older adults in the context of otherwise intact brain potentials. This result could not be attributed to uncertainty about the required response in older adults. Experiment 2 revealed impaired performance and reduced response- and feedback-related ERNs of older adults in a probabilistic learning task. These age changes could be simulated by manipulation of a single parameter of the neurocomputational model, this manipulation corresponding to weakened phasic activity of the mesencephalic dopamine system.     

The demands of an ongoing activity influence the success of event-based prospective memory

Four experiments were conducted to evaluate whether event-based prospective memory would be sensitive to the concurrent demands of the ongoing activity in which intention-related cues were embedded. In Experiments 1 and 2, random alternation between two judgments in the ongoing task reduced prospective memory as compared with having a single task throughout. In Experiment 3, participants' making two binary judgments on every trial resulted in worse prospective memory than did their making single four-alternative judgments. In Experiment 4, participants' making two related judgments resulted in better prospective memory than did their making two unrelated judgments. The results are consistent in spirit with a production rule account of the processing resources that are available when intention-related cues are encountered. Therefore, event-based prospective memory can inversely covary with the cognitive demands of the ongoing activity.