Robert M. Stelmack

The effect of response execution on P3 latency, reaction time, and movement time

This study examined the effect of response selection and execution on P3 latency during the performance of simple reaction time (RT) and stimulus-response compatibility tasks. Response time on these tasks was defined in terms of RT and movement time (MT). Event-related brain potentials were recorded from 67 female participants concurrently with the performance measures. On the simple RT task, the distance of the response button from the home button was varied (7, 15, and 23 cm). When stimulus evaluation demands were minimal, response execution affected P3 latency, with increased response button distance resulting in increased P3 latency. However, these movement effects were modest, and in most protocols, would not be a confounding factor. The stimulus-response compatibility task examined the interaction of stimulus evaluation demands and response requirements. RT, MT, and P3 latency were affected by stimulus congruency, whereas RT and P3 amplitude were affected by response compatibility.

Personality, Reaction Time, and Event-Related Potentials

Reaction time (RT), movement time (MT), and the amplitude and latency of the P300 event-related potential were recorded from 30 Ss during the performance of 6 simple cognitive tasks. Extraversion was negatively associated with MT, a result that endorses the view that extraversion is determined, in part, by individual differences in motor mechanisms. Higher neuroticism scores were associated with faster P300 latency, a measure that is regarded as an index of stimulus evaluation time that is independent of response production. Paradoxically, higher neuroticism scores were associated with slower RT, a measure that is also regarded as an index of speed of information processing. Higher psychoticism scores were associated with smaller P300 amplitude, an effect that may be indicative of less attentional effort invested in the tasks. The analyses of individual differences in the response to sensory stimulation and in the expression of motor responses are important sources of evidence for several proposals that have been put forward in the explanation of personality differences, notably extraversion, impulsiveness, and anxiety (Barratt, 1972; Brebner & Cooper, 1974; H. J. Eysenck, 1957; Newman, 1987; Stelmack, 1985). The present article aims to articulate differences in the processing of stimuli and production of responses that are relevant to the biological bases of those personality dimensions by exploiting relatively recent refinements in eventrelated potential (ERP) and reaction time (RT) measures that are recorded during the performance of simple cognitive tasks. This article addresses several questions that have emerged in the study of individual differences in extraversion and impulsiveness. At this time, there is a good deal of evidence from research using both behavioral and psychophysiological measures that demonstrates the greater sensory reaction to simple physical stimulation for introverts than extraverts (Stelmack, 1990). However, it is unclear whether these effects reflect differences at early stages of stimulus input, central stimulus analysis, or both. There is also a literature spanning 30 years that affirms differences between extraverts and introverts and between high- and low-impulsive subjects in their performance on various tasks that assess speed of responding and motor control (Barratt & Patton, 1983; Stelmack, 1985). Again, it is not clear whether these effects involve differences in central processing, motor response, or both. This issue is complicated because impulsiveness can be described as a complex construct composed of facets of extraversion, neuroticism, and psychoticism (H. J.

Intelligence, reaction time, and event-related potentials ☆

Event-related potentials and reaction time (RT) were recorded concurrently during the performance of six simple cognitive tasks for subjects (N = 30) who varied in mental ability. P300 latency to the target stimulus increased with increasing task difficulty in the same manner as RT on these tasks. P300 latency to the target stimulus was inversely related to mental ability, particularly for the more difficult paired-stimuli tasks. The first unrotated factor extracted from the intercorrelation of P300 latency to the target stimuli on these tasks defined a general P300 latency factor that accounted for 41% of the variance. The P300 latency factor scores were inversely related to general intelligence factor scores, (−.36, p < .05). The relationship between P300 latency and RT as distinguished from movement time, was negligible. These results suggest that P300 latency and RT may assess the stimulus-evaluation time and response-production time components of cognitive information processing, respectively, that vary inversely with general intelligence.

Recognition memory for words and event-related potentials: a comparison of normal and disabled readers

Visual event-related potentials elicited during a word-recognition memory task were examined for groups of normal and disabled readers (RD). The strong association of reading ability with recognition memory performance endorsed the appropriateness of this signal detection paradigm as a reading-related task. Enhanced amplitude of the P200 component for the RD group was evident during both the acquisition and recognition series and it is indicative of differences at an early sensory stage of item encoding and retrieval. Normal readers displayed greater N400 amplitude than the RD group during both the acquisition and recognition series, an effect which is consistent with more extensive semantic evaluation or memory search that is attributed to that component. In the absence of any remarkable differences in P300 amplitude between groups, the poorer recognition memory performance for the RD group may not be attributable to attentional deficits.

Intelligence and the effects of perceptual processing demands, task difficulty and processing speed on P300, reaction time and movement time

Abstract Event-related potentials (ERPs) were recorded to the memory set and probe stimuli in a Sternberg memory-scanning task and compared to intelligence scores on the Multidimensional Aptitude Battery (MAB). The memory set was changed on each trial and all items in the memory set were presented simultaneously. Only the probe stimulus required a decision and response. P300 amplitude to the memory set increased as the memory set size increased; this is thought to be a result of the effects of demands for processing resources. A pattern of weak negative correlations were observed between P300 amplitude to the memory set and MAB scores. In contrast, P300 amplitude to the probe stimulus decreased with increases in memory set load and there was a pattern of weak positive correlations with MAB scores. It is suggested that P300 amplitude to the memory set is affected by task difficulty. The latency of the P300 component of the ERP was used as an indicator of the relative speed of information processing. This allows the assessment of processing speed without requiring a physical response. Higher-ability participants displayed longer P300 latency to the memory set stimulus than lower-ability participants while there was no discernable effect on P300 latency to the probe stimulus. This contradicts a pure speed of processing explanation of the relation between P300 latency and intelligence. The longer P300 latency to the memory set suggests that higher-ability participants devoted more time to stimulus analysis and planning than-lower ability participants.

Movement time differentiates extraverts from introverts

Abstract 67 female subjects who were classified on the Eysenck Personality Questionnaire-Revised were compared on simple reaction time and stimulus-response compatibility tasks. Response time on these tasks was defined in terms of reaction time (RT) and movement time (MT). On the simple reaction time task, the distance of the target button from the home button was varied. The stimulus-response compatibility task examined the interaction of extraversion with stimulus evaluation demands and response requirements. For both tasks, and across all conditions, the MTs of extraverts were faster than those of the introverts, but no relation with RT was observed. These results support the view that individual differences in extraversion are influenced by differences in fundamental motor mechanisms.

Extraversion, sensation seeking and electrodermal response: Probing a paradox

Abstract Extraversion and psychoticism are thought to relate inversely to electrodermal response amplitude. Paradoxically, sensation-seeking scales, which correlate positively with extraversion and psychoticism, have shown a positive relation to electrodermal response amplitude. In the present inquiry, inverse relationships were obeserved for extraversion and psychoticism with the electrodermal response to visual stimuli. Sensation seeking was also negatively related to the magnitude of the initial electrodermal response to pictures. A lowered response to words for low sensation seekers was observed that appeared to be influenced by skin conductance level.

EXTRAVERSION AND AUDITORY SENSITIVITY TO HIGH AND LOW FREQUENCY

The sensitivity of 10 extraverts, 10 ambiverts, and 10 introverts to auditory stimuli was determined by a signal detection procedure. Under the low-frequency condition, introverts were significantly more sensitive than extraverts. Under the high-frequency condition, extraverts showed a significant increase in sensitivity, the introverts tended to show a relative decrease in sensitivity. Results endorse Eysencks proposed relation of extraversion and the reticular formation arousal system.

An event-related potential analysis of extraversion and individual differences in cognitive processing speed and response execution.

Individual differences in cognitive processing speed and response execution were examined in relation to extraversion. Event-related potentials (ERPs) were recorded concurrently with reaction time and movement time (MT) measures as participants (N = 67) performed simple reaction time and stimulus-response compatibility tasks. Slower processing speed for extraverts, as indicated by longer latency of a late positive ERP wave, P3, was only evident in conditions in which stimulus information was in conflict with response selection demands. As previously reported, the salient effect in all conditions of both tasks was faster MT for extraverts, an effect that is indicative of differences in fundamental motor processes. On the simple reaction time task, amplitudes of the N1 component, an early negative ERP wave, were smaller for extraverts than for introverts in response to auditory tones, an effect that affirms the enhanced sensory reactivity of introverts to punctate physical stimuli.

Power functions of loudness magnitude estimations and auditory brainstem evoked responses

The correspondence between subjective and neural response to change in acoustic intensity was considered by deriving power functions from subjective loudness estimations and from the amplitude and latency of auditory brainstem evoked response components (BER). Thirty-six subjects provided loudness magnitude estimations of 2-sec trains of positive polarity click stimuli, 20/sec, at intensity levels ranging from 55 to 90 dB in 5-dB steps. The loudness power function yielded an exponent of .48. With longer trains of the same click stimuli, the exponents of BER latency measures ranged from -.14 for wave I to -.03 for later waves. The exponents of BER amplitude-intensity functions ranged from .40 to .19. Although these exponents tended to be larger than exponents previously reported, they were all lower than the exponent derived from the subjective loudness estimates, and a clear correspondence between the exponents of the loudness and BER component intensity functions was not found.