Reaction time,movement time,and intelligence

Speed of information processing is measured in terms of reaction time (RT) and movement time (MT) to five stimulus displays which differ in the amount of information transmitted, over a range from 0 to 3 bits of information. RT, but not MT, increases as a linear function of the number of bits in the stimulus display. RT and MT show reliable individual differences which are significantly correlated with intelligence as measured by Raven's Standard Progressive Matrices.     

Reaction time and response dynamics

The experiments reported were designed to examine the relationship between reaction time and the response dynamics of a finger-press task. Experiments 1 and 2 manipulated force duration and peak force level in both simple and choice reaction-time paradigms. Experiment 3 constrained both force duration and peak force, leading to independent changes in the rate of force production. The findings from all three experiments suggest that the rate of force production, rather than force duration, is the key response parameter determining reaction time. Reaction time decreased as an exponential function of rate of force production independent of force duration and peak force.     

Laterality of the frontal aslant tract (FAT) explains externalizing behaviors through its association with executive function

We investigated the development of a recently identified white matter pathway, the frontal aslant tract (FAT) and its association with executive function and externalizing behaviors in a sample of 129 neurotypical male and female human children ranging in age from 7 months to 19 years. We found that the FAT could be tracked in 92% of those children, and that the pathway showed age‐related differences into adulthood. The change in white matter microstructure was very rapid until about 6 years, and then plateaued, only to show age‐related increases again after the age of 11 years. In a subset of those children (5–18 years; n = 70), left laterality of the microstructural properties of the FAT was associated with greater attention problems as measured by the Child Behavior Checklist (CBCL). However, this relationship was fully mediated by higher executive dysfunction as measured by the Behavior Rating Inventory of Executive Function (BRIEF). This relationship was specific to the FAT—we found no relationship between laterality of a control pathway, or of the white matter of the brain in general, and attention and executive function. These findings suggest that the degree to which the developing brain favors a right lateralized structural dominance of the FAT is directly associated with executive function and attention. This novel finding provides a new potential structural biomarker to assess attention deficit hyperactivity disorder (ADHD) and associated executive dysfunction during development.     

Reaction time measures of backward masking

We employed both simple and choice reaction time (RT) paradigms in which the subjects were required to respond to 3.0 cycles per degree (c/d) square-wave gratings presented to one eye, while checkerboard masks were presented at various stimulus-onset asynchronies to the other eye. No masking was evident using the simple RT paradigm, but with the choice RT task, checkerboard masks presented to the contralateral eye of three subjects resulted in substantial decreases in response speed when the test preceded the mask by stimulus-onset asynchronies of 25 to 75 ms. Masks that contained lower fundamental spatial frequencies (1.0 c/d) than the target were more effective than masks containing fundamental spatial frequencies (6.0 c/d) higher than the target, while masks that contained fundamental components identical to those in the target (3.0 c/d) produced maximum masking. The results offer support for the sustained-transient theory of visual processing and validate RT as a technique for examining spatio-temporal factors in masking.     

Reaction time task as unconditional stimulus

The present study was conducted to demonstrate classic conditioning in electrodermal (ED) and heart rate (HR) responses by using a nonaversive reaction time (RT) task as unconditional stimulus (US). Three groups of 12 subjects each were studied to test the efficacy of this US procedure by varying the essential components of the RT task-US between groups. Eight seconds differential delay conditioning was applied in each group. Simple geometric features (square, cross) displayed on a TV screen were used as CS+ and CS−. RT task consisted of a nonaversive tone (72 dBA, 1000 or 1200 Hz) and a motor response (pressing a button with the left index finger). Subjects were asked to respond as soon as the tone stimulus was presented. The three groups received different stimulus sequences during the 16-trial acquisition phase only. In one group (Group C1), CS+ was followed by a tone to which subjects were to respond, whereas CS− was not followed by a tone. Similarly, in a second group (Group H), CS+ was followed by a tone, whereas CS− was not; however, subjects of Group H (habituation group) were not required to respond to the tone. In a third group, (Group C2) CS+ was followed by a tone to which subjects were to respond, while CS− was followed by a different tone requiring no response. According to analysis of Group C1 data, differential conditioning was obtained in each response measure. Group H displayed habituation in each response measure obtained. In Group C2, differential conditioning was obtained in the second latency window of ED responses only. In all trials, first-interval anticipatory ED responses and HR responses did occur during acquisition, but were not differentiated with respect to the CS conditions. Although the results of Group C2 need further exploration, differential conditioning of HR and in all latency windows of ED responses was demonstrated by the use of a nonaversive RT task as US.     

Reaction time task as unconditional stimulus

Nonaversive unconditional stimuli (USs) are seldom used in human classic conditioning of autonomic responses. One major objection to their use is that they produce deficits in electrodermal (ED) second- and third-interval response conditioning. However, a nonaversive reaction time (RT) task that includes feedback of success has been shown to be an effective US while avoiding this disadvantage (Lipp and Vaitl 1988). The present study compared this new RT task (RT-new) with a traditional RT task (RT-old) and with a standard aversive US (shock) in differential classic conditioning of ED, heart rate (HR), and digital pulse volume (DPV) responses. Eight-second-delay differential conditioning was applied in three groups of 12 subjects each. Simple geometric features (square, cross) displayed on a television screen served as conditional stimuli (CS⁺ and CS^?). In acquisition, there were no statistically significant differences among the groups; differential conditioning did occur in HR, first- and second-interval ED responses, and first-interval DPV responses. Separate analyses within each group, however, revealed that there was no second-interval ED conditioning in the RT-old group. During extinction, neither DPV nor second-interval ED conditioning could be obtained, whereas HR and first-interval ED conditioning occurred in each group. In third-interval omission ED responses, RT-old and shock groups exhibited extinction, while response differentiation was maintained in the RT-new group throughout extinction. The RT task including feedback proved to be as reliable a US as a standard aversive US, whereas application of a traditional RT task again yielded some weaknesses in second-interval ED conditioning.     

Reaction time and movement time after active and passive smoking

Reaction time and movement time were studied following active and passive smoking in two groups of 20 women. All subjects were tested under a clean air and smoky air condition and the results showed that, while there was no difference between groups for either measure in the clear air condition, the active smokers had faster reaction time and movement time in the smoky air condition. Smoky air had no significant effect on the responses of the passive smoking group.     

Desire satisfaction,death, and time

Desire satisfaction theories of well-being and deprivationism about the badness of death face similar problems: desire satisfaction theories have trouble locating the time when the satisfaction of a future or past-directed desire benefits a person; deprivationism has trouble locating a time when death is bad for a person. I argue that desire satisfaction theorists and deprivation theorists can address their respective timing problems by accepting fusionism, the view that some events benefit or harm individuals only at fusions of moments in time. Fusionism improves on existing solutions to the timing problem for deprivationism because it locates death’s badness at the same time as both the victim of death and death itself, and it accounts for all of the ways that death is bad for a person. Fusionism improves on existing solutions to the problem of temporally locating the benefit of future and past-directed desires because it respects several attractive principles, including the view that the intrinsic value of a time for someone is determined solely by states of affairs that obtain at that time and the view that intrinsically beneficial events benefit a person when they occur.     

Reaction time and probability on isolated terms

The reaction-time probability effect on isolated trials was found to be asymmetrical in an experiment on 64 college students. There was a large drop in RT for a high-probability probe trial embedded in a block of low-probability trials, but a much smaller rise for a low-probability trial embedded in high-probability trials. Thus, low- but not high-probability responses seem to be influenced by characteristics of the trial block. If the basis of the probability effect were the strategic placement of the criterion for response initiation, symmetrical results should have been obtained. A motivational account which accords with the present data is that the subject is ordinarily willing to prepare but is averse to doing so in some (not entirely specified) low-probability circumstances.     

Reaction time, race, and racism

The claim (Jensen, 1975) that blacks are slower than whites in choice (but not simple) reaction time is examined. It is false. The claim (Jensen, 1985) that Muhammad Ali was shown to have a “very average” reaction time is examined. It is false. The claim (Vernon & Jensen, 1984) that an unpublished technical report showed blacks to be inferior to whites on a relatively content-free mental processing task is examined. It is false. Suggestions are made concerning relevant questions that might be addressed by students of race differences in intelligence.     

Reaction time, intelligence, and attention

The roles of attention in reaction time and in the relationships among reaction time, intelligence, and achievement were analyzed. The subjects were 105 seventh-grade children. The results were generally consistent with most studies involving the Hick paradigm: both mean reaction time and the standard deviation of reaction time correlated with the intelligence and achievement measures used. Reaction time measures were correlated with attention and perceptual speed as well as with general intelligence, or g. Implications of these results for current theories linking reaction time and intelligence are discussed.     

Reaction time and accuracy in individuals with aphasia during auditory vigilance tasks

Research indicates that attentional deficits exist in aphasic individuals. However, relatively little is known about auditory vigilance performance in individuals with aphasia. The current study explores reaction time (RT) and accuracy in 10 aphasic participants and 10 nonbrain-damaged controls during linguistic and nonlinguistic auditory vigilance tasks. Findings indicate that the aphasic group was less accurate during both tasks than the control group, but was not slower in their accurate responses. Further examination of the data revealed variability in the aphasic participants' RT contributing to the lower accuracy scores.     

Reaction time indices of attention deficits in boys with disruptive behavior disorders

Boys with diagnoses in the disruptive behavior disorder (DBD) spectrum and normal controls were tested in two reaction time (RT) experiments. In Experiment I simple warned RT was measured and the length and regularity of the preparatory intervals were varied in order to study sustained attention in the sense of preparation. With age and IQ controlled, DBD boys had slower and more variable RT overall than controls and showed generally more pronounced effects of variations in the length and sequence of the preparatory intervals. The results suggest that DBD boys are subject to lapses of attention which are increased by a relatively long preparatory interval, and that they have a particular problem with temporal uncertainty. In Experiment II some aspects of selective attention were studied in a paradigm in which stimulus modality uncertainty and response selection were varied. DBD boys showed greater effects of modality uncertainty but not response selection than controls. No differences between subdiagnoses within the DBD spectrum could be demonstrated.     

Reaction time and diazepam plasma concentration in subjects with normal gastric pH

The present study investigated the relationship of reaction time with the plasma concentration of four different formulations of diazepam (liquid, original, new, and generic). On four separate days, over a 4-month period, subjects with normal gastric pH (N=7) were administered each of the diazepam formulations. Blood samples were obtained prior to each dose and at subsequent intervals. Likewise, reaction times were evaluated prior to dosing and then at ten different intervals post-dosing. As hypothesized, reaction time performance was associated with plasma diazepam concentration, regardless of formulation type. This suggests that reaction time is a sensitive measure of cerebral functioning for individuals who are treated with diazepam. In addition to providing a measure of drug effects on cognitive functioning, the results of this study have implications concerning possible hazards of operating machinery or driving motor vehicles for individuals being treated with diazepam.     

Reaction time and diazepam plasma concentration in subjects with normal gastric pH

The present study investigated the relationship of reaction time with the plasma concentration of four different formulations of diazepam (liquid, original, new, and generic). On four separate days, over a 4-month period, subjects with normal gastric pH (N=7) were administered each of the diazepam formulations. Blood samples were obtained prior to each dose and at subsequent intervals. Likewise, reaction times were evaluated prior to dosing and then at ten different intervals post-dosing. As hypothesized, reaction time performance was associated with plasma diazepam concentration, regardless of formulation type. This suggests that reaction time is a sensitive measure of cerebral functioning for individuals who are treated with diazepam. In addition to providing a measure of drug effects on cognitive functioning, the results of this study have implications concerning possible hazards of operating machinery or driving motor vehicles for individuals being treated with diazepam.