Inconsistency in Reaction Time Across the Life Span.

Inconsistency in latency across trials of 2-choice reaction time data was analyzed in 273 participants ranging in age from 6 to 81 years. A U-shaped curve defined the relationship between age and inconsistency, with increases in age associated with lower inconsistency throughout childhood and higher inconsistency throughout adulthood. Differences in inconsistency were independent of practice, fatigue, and age-related differences in mean level of performance. Evidence for general and specific variability-producing processes was found in those aged less than 21 years, whereas only a specific process, such as attentional blocks, was evident for those 21 years and older. The findings highlight the importance of considering moment-to-moment changes in performance in psychological research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuroticism as Mental Noise: A Relation Between Neuroticism and Reaction Time Standard Deviations.

Those higher in neuroticism are often more variable in their behavior and experience. On the basis of this observation, the authors hypothesized that the trait of neuroticism might be correlated with the variability of performance pertaining to relatively basic cognitive operations. Three studies involving 242 college undergraduates supported this prediction in that neuroticism correlated positively with the variability of performance across trials of reaction time tasks. These results link neuroticism to cognitive noise that intervenes between stimulus and response. Such noise has been associated with executive dysfunctions (e.g., frontal lobe injury) in previous research. The present findings are potentially useful for understanding why neuroticism often correlates with variations in the functionality of cognition and behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The Effects of Spatial Stimulus-Response Compatibility on Choice Time Production Accuracy and Variability.

Five experiments examined the relations between timing and attention using a choice time production task in which the latency of a spatial choice response is matched to a target interval (3 or 5 s). Experiments 1 and 2 indicated that spatial stimulus-response incompatibility increased nonscalar timing variability without affecting timing accuracy and that choice reaction time practice reduced choice time production variability. These data support a "temporal discounting" model in which response choice and timing occur in series, but the interval timed is shortened to account for nontemporal processing. In Experiment 3, feedback and anticipation task demands improved choice time production accuracy. In Experiments 4 and 5, the delay between the start-timing and choice-decision signals interacted with choice difficulty to affect choice time production accuracy and variability when timing a 3- but not a 5-s interval, suggesting that attention mediates timing before and after an interruption in timing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maintenance of Response Readiness in Patients With Parkinson's Disease: Evidence From a Simple Reaction Time Task.

The authors explored the effect of Parkinson's disease (PD) on the generation and maintenance of response readiness in a simple reaction time task. They compared performance of idiopathic PD patients without dementia, age-matched controls, and younger controls over short (1-, 3-, and 6-s) and long (12- and 18-s) foreperiod intervals. After each trial, the authors probed memory for visual information that also had to be maintained during the trial interval. Patients and controls did not differ overall in their ability to maintain readiness over long delays. However, within the PD group only, errors in maintaining visual information were correlated with difficulty in maintaining readiness, suggesting that systems impaired in PD may facilitate the maintenance of processing in both motor and cognitive domains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Comparison of Sequential Sampling Models for Two-Choice Reaction Time.

The authors evaluated 4 sequential sampling models for 2-choice decisions--the Wiener diffusion, Ornstein-Uhlenbeck (OU) diffusion, accumulator, and Poisson counter models--by fitting them to the response time (RT) distributions and accuracy data from 3 experiments. Each of the models was augmented with assumptions of variability across trials in the rate of accumulation of evidence from stimuli, the values of response criteria, and the value of base RT across trials. Although there was substantial model mimicry, empirical conditions were identified under which the models make discriminably different predictions. The best accounts of the data were provided by the Wiener diffusion model, the OU model with small-to-moderate decay, and the accumulator model with long-tailed (exponential) distributions of criteria, although the last was unable to produce error RTs shorter than correct RTs. The relationship between these models and 3 recent, neurally inspired models was also examined. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Task-contingent conscientiousness as a unit of personality at work.

The present study examined the viability of incorporating task-contingent units into the study of personality at work, using conscientiousness as an illustrative example. We used experience-sampling data from 123 managers to show that (a) momentary conscientiousness at work is contingent on the difficulty and urgency demands of the tasks people are engaged in, (b) there are significant and stable differences between people in the extent to which their conscientiousness behaviors are contingent on task demands, and (c) individual differences in task-contingent conscientiousness are related to, though distinct from, individual differences in trait conscientiousness. We also provide evidence in relation to (a) need for cognition as a possible antecedent of task-contingent conscientiousness and (b) adaptive performance on a cognitive task as a possible consequence of it. We discuss the theoretical implications of our findings for the cognitive nature of personality and the way in which conscientiousness is expressed at work. Practical implications in relation to the predictive function of personality and applications that focus on behavioral change are also discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neural underpinnings of within-person variability in cognitive functioning.

Increased intraindividual variability (IIV), reflecting within-person fluctuations in behavioral performance, is commonly observed in aging as well as in select disorders including traumatic brain injury, schizophrenia, attention-deficit hyperactivity disorder (ADHD), and dementia. Much recent progress has been made toward understanding the functional significance of IIV in cognitive performance (MacDonald, Nyberg, & B?ckman, 2006) and biological information processing (Stein, Gossen, & Jones 2005), with parallel efforts devoted to investigating the links between older adults’ deficient neuromodulation and their more variable neuronal and cognitive functions (B?ckman, Nyberg, Lindenberger, Li, & Farde, 2006). Despite these advances in the study of IIV, there has been little empirical examination of underlying neural correlates and virtually no synthesis of extant findings. The present review summarizes the accumulating empirical evidence linking age-related increases in IIV in cognitive performance to neural correlates at anatomical, functional, neuromodulatory, and genetic levels. Computational theories of neural dynamics (e.g., Li, Lindenberger, & Sikstr?m, 2001) are also introduced to illustrate how age-related neuromodulatory deficiencies may contribute to increased neuronal noise and render information processing in aging neurocognitive systems to be less robust. The potential benefits of stochastic resonance and external noise are also discussed with respect to processing subthreshold stimuli (e.g., Li, von Oertzen, & Lindenberger, 2006). We conclude by highlighting important challenges and outstanding research issues that remain to be answered in the study of IIV. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in core affect variability and their relationship to personality and psychological adjustment.

How people's feelings change across time can be represented as trajectories in a core affect space defined by the dimensions of valence and activation. In this article, the authors analyzed individual differences in within-person affective variability defined as characteristics of core affect trajectories, introducing new ways to conceptualize affective variability. In 2 studies, participants provided multiple reports across time describing how they were feeling in terms of core affect. From these data, characteristics of participants' core affect trajectories were derived. Across both studies, core affect variability was negatively related to average valence, self-esteem, and agreeableness, and it was positively related to neuroticism and depression. Moreover, spin, a measure of how much people experienced qualitatively different feelings within the core affect space, was related more consistently to trait measures of adjustment and personality than other measures of within-person variability, including widely used measures of within-person single-dimension standard deviations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reaction time in the cold.

"Visual RT's were elicited from 620 soldiers sorted into 14 different groups representing a variety of ambient temperatures, windspeeds and windchills… . 1. At low windspeed… low ambient temperature has no effect on RS… . [reciprocal of RT]. 2. At windspeeds of 10 mph and greater, low ambient temperature produces a significant decrease in RA. 3. Windspeed produces a significant decrease in RS. 4. Mild exercise produces a small recover in RS. 5. If men of low 'physiological cold tolerance' are removed from the more severe environmental conditions and if Ss wear protective clothing, RS is essentially a linear decreasing function of windchill." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reaction time as a measure of perceptual vigilance.

Reviews the use made of reaction time as an index of performance deterioration in monitoring tasks, with special reference to the hypothesis that reaction time and detection rate are correlated indices of perceptual vigilance. It is concluded that this is the case, and a theoretical model relating the 2 indices to changes in vigilance occurring with time on task is proposed. (2 p. ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attention: Reaction Time and Accuracy Reveal Different Mechanisms.

The authors propose that there are 2 different mechanisms whereby spatial cues capture attention. The voluntary mechanism is the strategic allocation of perceptual resources to the location most likely to contain the target. The involuntary mechanism is a reflexive orienting response that occurs even when the spatial cue does not indicate the probable target location. Voluntary attention enhances the perceptual representation of the stimulus in the cued location relative to other locations. Hence, voluntary attention affects performance in experiments designed around both accuracy and reaction time. Involuntary attention affects a decision as to which location should be responded to. Because involuntary attention does not change the perceptual representation, it affects performance in reaction time experiments but not accuracy experiments. The authors obtained this pattern of results in 4 different versions of the spatial cuing paradigm. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intraindividual variability in positive and negative affect over 45 days: Do older adults fluctuate less than young adults?

Opposing scenarios about age-related increases and decreases in intraindividual variability are found in the literature: Whereas accumulating evidence indicates that cognitive functioning is characterized by an age-related increase of short-term variability, age-related decreases in variability could be expected in affective states on the basis of theories of emotion regulation and self development. We examined age differences in intraindividual variability of positive affect (PA) and negative affect (NA) and in contingencies among daily affect, daily stress, and daily events using up to 45 daily assessments of 18 young (20–30 years) and 19 older (70–80 years) adults. Whereas age groups differed little in average affect levels, older adults showed significantly less variability in PA and NA than young adults. Age differences accounted for greater variance in variability than personality factors. Multilevel modeling indicated that for young but not older adults, PA was higher (lower) on days with a positive (negative) event, and NA was lower on days with a positive event. There were no age differences in daily affect reactivity to appraised stress severity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inter- and Intraindividual Variability in Recognition Memory: Effects of Aging and Estrogen Use.

Traditionally, studies of cognitive aging have focused on comparing the average performance of younger and older adults, whereas variability around the mean has been attributed to task-irrelevant noise. The present study examined the hypothesis that variability in memory performance increases with age and that estrogen helps temper age-related increases in variability. Postmenopausal estrogen users, estrogen and progestin (est + prog) users, and nonusers, as well as younger women, completed 16 blocks of an item-source memory task. Older women showed greater variability than younger women on measures of dispersion and consistency. Estrogen users, but not est + prog users, performed more consistently than nonusers. Overall, age-related increases in variability differed with the type of variability measured, and estrogen use, but not est + prog use, appeared to reduce age-related increases in at least 1 form of variability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Proprioceptive Perception of Phase Variability.

Previous work has established that judgments of relative phase variability of 2 visually presented oscillators covary with mean relative phase. Ninety degrees is judged to be more variable than 0° or 180°, independently of the actual level of phase variability. Judged levels of variability also increase at 180°. This pattern of judgments matches the pattern of movement coordination results. Here, participants judged the phase variability of their own finger movements, which they generated by actively tracking a manipulandum moving at 0°, 90°, or 180°, and with 1 of 4 levels of Phase Variability. Judgments covaried as an inverted U-shaped function of mean relative phase. With an increase in frequency, 180° was judged more variable whereas 0° was not. Higher frequency also reduced discrimination of the levels of Phase Variability. This matching of the proprioceptive and visual results, and of both to movement results, supports the hypothesized role of online perception in the coupling of limb movements. Differences in the 2 cases are discussed as due primarily to the different sensitivities of the systems to the information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Examining the Time Course of Indexical Specificity Effects in Spoken Word Recognition.

Variability in talker identity and speaking rate, commonly referred to as indexical variation, has demonstrable effects on the speed and accuracy of spoken word recognition. The present study examines the time course of indexical specificity effects to evaluate the hypothesis that such effects occur relatively late in the perceptual processing of spoken words. In 3 long-term repetition priming experiments, the authors examined reaction times to targets that were primed by stimuli that matched or mismatched on the indexical variable of interest (either talker identity or speaking rate). Each experiment was designed to manipulate the speed with which participants processed the stimuli. The results demonstrate that indexical variability affects participants' perception of spoken words only when processing is relatively slow and effortful. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reinforced Variability in Animals and People: Implications for Adaptive Action.

Although reinforcement often leads to repetitive, even stereotyped responding, that is not a necessary outcome. When it depends on variations, reinforcement results in responding that is diverse, novel, indeed unpredictable, with distributions sometimes approaching those of a random process. This article reviews evidence for the powerful and precise control by reinforcement over behavioral variability, evidence obtained from human and animal-model studies, and implications of such control. For example, reinforcement of variability facilitates learning of complex new responses, aids problem solving, and may contribute to creativity. Depression and autism are characterized by abnormally repetitive behaviors, but individuals afflicted with such psychopathologies can learn to vary their behaviors when reinforced for so doing. And reinforced variability may help to solve a basic puzzle concerning the nature of voluntary action. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intraindividual Variability May Not Always Indicate Vulnerability in Elders' Cognitive Performance.

This study examined consistency of performance, or intraindividual variability, in older adults' performance on 3 measures of cognitive functioning: inductive reasoning, memory, and perceptual speed. Theoretical speculation has suggested that such intraindividual variability may signal underlying vulnerability or neurologic compromise. Thirty-six participants aged 60 and older completed self-administered cognitive assessments twice a day for 60 consecutive days. Intraindividual variability was not strongly correlated among the 3 cognitive measures, but, over the course of the study, intraindividual variability was strongly intercorrelated within a task. Higher average performance on a measure was associated with greater performance variability, and follow-up analyses revealed that a higher level of intraindividual variability is positively associated with the magnitude of a person's practice-related gain on a particular measure. The authors argue that both adaptive (practice-related) and maladaptive (inconsistency-related) intraindividual variability may exist within the same individuals over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Variability of performance in a vigilance task.

An experiment was conducted to determine the effect of signal pattern and frequency on the variability of S's performance in a vigilance task. Ss were 12 male college students who watched 3 dials during 3 consecutive 27-min. periods. Real signals occurred alone in 1 period while 2 different patterns of dummy signals were added in the other 2 periods. It was found that dummy signals which occurred at semiregular intervals were more effective in reducing S's variability than those which occurred at nonregular intervals. It was also found that variability increased with time. It is concluded that use of a semiregular pattern of dummy signals would be one way of improving performance on a vigilance task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the Locus of Speed-Accuracy Trade-Off in Reaction Time: Inferences From the Lateralized Readiness Potential.

Lateralized readiness potentials (LRPs) were used to determine the stage(s) of reaction time (RT) responsible for speed-accuracy trade-offs (SATs). Speeded decisions based on several types of information were examined in 3 experiments, involving, respectively, a line discrimination task, lexical decisions, and an Erikson flanker task. Three levels of SAT were obtained in each experiment by adjusting response deadlines with an adaptive tracking algorithm. Speed stress affected the duration of RT stages both before and after the start of the LRP in all experiments. The latter effect cannot be explained by guessing strategies, by variations in response force, or as an indirect consequence of the pre-LRP effect. Contrary to most models, it suggests that SAT can occur at a late postdecisional stage. (PsycINFO Database Record (c) 2010 APA, all rights reserved)