Foreperiod Conditions Research Articles

Visual processing is diminished during movement execution.

Recent research has suggested that visual discrimination and detection may be enhanced during movement preparation and execution, respectively. The current study examined if visual perceptual processing is augmented prior to or during a movement through the use of an Inspection Time (IT) task. The IT task involved briefly presenting (e.g., 15–105 ms) a “pi” figure with differing leg lengths, which was then immediately masked for 400 ms to prevent retinal afterimages. Participants were subsequently required to choose which of the two legs was longer. In Experiment 1, participants (n = 28) completed the IT task under three movement conditions: no-movement (NM), foreperiod (FP), and peak velocity (PV). In the NM condition, participants solely engaged in the IT paradigm. In the FP condition, the IT stimulus was presented prior to movement execution when response planning was expected to occur. Finally, in the PV condition, participants made a rapid movement to a target, and the IT stimulus was presented when their limb reached peak velocity. In Experiment 2, participants (n = 18) also performed the IT task in the PV and NM condition; however, vision of the limb’s motion was made available during the PV trials (PV-FV) to investigate the potential influence of visual feedback on IT performance. Results showed no significant differences in performance in the IT task between the NM and FP conditions, suggesting no enhancement of visual processing occurred due to response preparation (Experiment 1). However, IT performance was significantly poorer in the PV condition in comparison to both the NM and FP conditions (Experiment 1), and was even worse when visual feedback was provided (Experiment 2). Together, these findings suggest that visual perceptual processing is degraded during execution of a fast, goal-directed movement.

Mean response times, variability, and skew in the responding of ADHD children: a response time distributional approach

Response time (RT) distributions from three fixed foreperiod conditions (2, 4, and 8 s) in a warned four-choice RT task were obtained for a group of boys with attention-deficit/hyperactivity disorder, combined type (ADHD; n=17) and for two groups of normal control boys (age-matched, n=18, and younger-aged, n=10). Quantitative measures of distributional shape were derived by fitting the ex-Gaussian distributional model to the individual RT data. Statistical results indicate that the ADHD distributions differ from the age-matched control distributions with respect to the size of the tail (larger for the ADHD boys), but differ from the younger control distributions with respect to the location of the leading edge (slower for the younger control boys). Receiver operating characteristic (ROC) results reveal that the ex-Gaussian exponential component is highly diagnostic of the ADHD boys.

Aging, Reaction Time, and Stages of Information Processing

Using Sternberg's (1969) Additive Factors Method (AFM), previous investigations in search of the locus of age-related slowing in reactive capacity have found conflicting results possibly due to inconsistencies in research methodologies. This experiment was conducted to examine age differences in the performance of AFM intratask manipulations of a reaction time task using both fixed and variable foreperiod conditions with subject testing at both naive and practiced skill levels. Twenty male subjects, ten young and ten old, performed a visual four-choice RT task with intratask manipulations of stimulus-degradation, stimulus-response compatibility, and response-stimulus intervals (RSIs were fixed at 0, 2, and 5 sec and variable with random presentations at 0, 2, and 5 sec), once when subjects were naive and again when practiced. The results varied by level of practice and RSI, but clearly the older subjects had difficulty with the intratask manipulations. The older subjects took twice as long, on the average, to respond. Interactions of age by compatibility suggest that, according to the AFM, with age comes inordinately long delays in the response selection stage of information processing. Conclusions are made with caution since this research points to limitations and methodological confounds which serve to explain many of the equivocal findings in previous studies.

Effects of Age and Practice on Attention and Stages of Information Processing Using CRT with Fixed and Variable Foreperiods

The results of previous investigations have found conflicting results on the locus of age-related slowing of reaction time using Additive Factors Method (Sternberg, 1969). This experiment was conducted to examine the differential effects of Additive Factors Method task manipulations using both fixed and variable foreperiod conditions with practice preceding a second day replication to quantify the interaction of these effects with skill. The results show that (1) practice is a major confounding for research involving RT tasks, (2) the locus of age effects may lie in the later response selection stage of processing, and (3) the effects of aging, practice and intra-task factors depend on the response-stimulus interval characterizing the RT task. This research has implications for improving research methodologies and understanding the nature of age-related slowing in central nervous system functions.

Individual differences in the effect of smoking on frontal-central distribution of the CNV: Some observations on smokers' control of attentional behaviour

A previous investigation of individual differences in cortical activation during smoking reported differential development of vertex CNV ‘O’ and ‘E’ wave components in introverted and extraverted smokers. In the present paper the frontal CNV recorded from 12 extraverted and 12 introverted smokers was analysed under simple and choice foreperiod conditions during sham and real smoking. Smokers were matched for age, sex and neuroticism. Analysis of variance revealed significant group by smoking session effects for the later ‘E’ wave component but not for the early ‘O’ wave component. ‘O’ wave negativity though more prominent in frontal regions particularly in extraverts tended to be more affected by foreperiod conditions than smoking sessions. In general smoking produced an increase in central negativity in extraverts, and a decrease in parietal positivity in introverts. These results challenge the stimulus-related/response-related separation of smoking effects made previously to account for early and late CNV component differences. It is suggested that a distinction of CNV components in terms of input (sensory) and output (motor) aspects may anyway be inappropriate. An attempt is made to relate CNV negativity/positivity topography differences to a motor model of attentional strategies differentially deployed during smoking. Extraverted smoker strategies may aim to relieve boredom, enhance readiness to act and so increase central negativity. Introverts may smoke to inhibit distraction, maintain a complex attentional set, and so these affect parietal positivity. It is further suggested that the pharmacological effects of nicotine are those of a generalized mild stressor which supplement the motor aspects of smoking in inducing more motivated performance. Some further predictions concerning the effect of smoking on cortical activity are discussed.

The contingent negative variation and individual differences in smoking behaviour

The aim of the experiment was to examine evidence for a relationship between extraversion, smoking effects, and event related cortical measures. Sixteen extraverted and 16 introverted smokers, drawn from the general population, and matched for age, sex and neuroticism, participated as paid volunteers. Vertex EEG and eye movements were recorded during an S 1–S 2–MR paradigm. Foreperiod duration varied between a regular interval series (1.25 sec) and an irregular interval series (1.25/4.00 sec) with both simple and choice reaction time conditions. Eight artefact free trials were averaged from each condition for each subject, within both a sham smoking and a real smoking session. Analysis of variance revealed significant personality group by sessions interaction effects for both CNV and VER measures. Peak CNV amplitude was found to be greater in extraverts during real smoking and greater in introverts during sham smoking sessions which supported previous findings relating to the biphasic arousing properties of smoking. However, component measures taken on the CNV waveforms under the longer foreperiod interval, indicated differences in shape as well as amplitude of the CNV responses elicited under smoking. In extraverted smokers the early ‘orienting’ component of the CNV was more pronounced during sham smoking, but during real smoking the later ‘E’ wave component became more prominent. Introverted smokers on the other hand showed a decrease in ‘E’ wave amplitude from sham to real smoking sessions. A model involving personality differences in attentional strategies employed during sham and real smoking sessions is proposed to account for CNV morphological differences. Group differences in EEG, performance and puff volume measures over foreperiod conditions suggested that smoking accompanied enhanced stimulus selectivity in introverts, but enhanced response preparation in extraverts. Possible brain mechanisms responsible for the interaction between nicotine effects and personality specific attentional strategies are discussed.

Sequential effects of foreperiod duration and conditional probability of the signal in a choice reaction time task

The aim of the present study was to determine whether the negative relationship usually found between reaction time and foreperiod duration in the variable foreperiod paradigm is entirely due to sequential foreperiod effects. It has been shown that when a particular foreperiod has been preceded by a longer one on the previous trial, reaction time is longer than when the preceding foreperiod was equal or shorter. This may be sufficient to explain the increase in reaction time observed for short foreperiods in variable foreperiod conditions. The present results show that, when sequential effects were controlled by the elimination of all trials where the foreperiod was shorter than the preceding one, the negative slope of the reaction time-foreperiod function diminished but did not disappear. The results suggest an interpretation of the role of conditional probability of stimulus arrival in terms of variation in the tendency to reprepare when the moment initially chosen for preparation appears to fall short of the moment at which the stimulus is actually presented.

Hospitalization and Simple Reaction Time

Previous studies have raised the question of the validity of using only hospitalized Ss as controls when the results are generalized to a non-hospitalized population. Twelve male hospitalized Ss and 12 male non-hospitalized Ss participated in a reaction time study using the visual and auditory modalities under constant 6-, 9-, and 15-sec. foreperiod conditions. The data showed significant differences between groups in all foreperiods with the auditory stimuli and the 15-sec. foreperiod with the visual stimulus. Results are discussed in terms of the use of hospitalized patients as controls in research and the differential effect of foreperiod and modality on the two groups studied.

Reaction time as a function of fixed vs. variable foreperiod in the squirrel monkey

A squirrel monkey was trained to press and hold down a lever in the presence of a blue light. Subsequent release of the lever on appearance of a white circle was reinforced with a food pellet. The monkey was tested under two different foreperiod conditions: (1) the white circle appeared at a variable period from 0-5 sec. following the lever press, and (2) the white circle appeared at a fixed 2 sec. interval following the lever press. The reaction time in the sessions with fixed foreperiod was consistently longer than the reaction time with variable foreperiod.

EFFECT OF MOTIVATING INSTRUCTIONS ON SIMPLE REACTION TIME.

Twenty-four male patients with no history of cerebral damage or psychosis and 24 non-hospitalized male Ss received 65 simple reaction time (RT) trials under constant 6-sec. foreperiod conditions. No preparatory signal was used. Time between onset of a visual stimulus and its termination by Ss depression of a telegraph key was the RT. Initially, all Ss received 35 trials followed by either success, failure, or standard instructions. Thirty additional trials were given. RTs of the hospitalized Ss were longer than those of the non-hospitalized Ss, but differences fell short of statistical significance. Differences between instruction subgroups were not significant, suggesting that motivating instructions do not affect simple RT performances.