摘要:

ABSTRACTReflex inhibition was investigated in young and elderly subjects as a function of prestimulus duration. In Experiment 1, tone prestimuli of 20 and 200 msec duration were presented at ISIs of 60, 120, 240, and 420 msec before the reflex‐eliciting, periorbital airpuff. Both age groups evidenced more eyeblink inhibition with the longer prestimulus. The heart rate response was primarily decelerative in both age groups. In young subjects, the initial deceleration was augmented by the prestimulus, particularly for the 200‐msec prestimulus, whereas the elderly heart rate response was unaffected. In Experiment 2, a gap in a continuous tone served as the prestimulus. In both young and elderly subjects, eyeblink inhibition increased as gap duration increased from 10 to 80 msec. The longest gap (120 msec) produced the most inhibition in the elderly, while inhibition decreased somewhat in young subjects between the 80 and 120 msec gaps. Heart rate was not affected by the gap prestimuli in either group. It was proposed that reflex inhibition is, in part, a function of the onset and offset transients of the prestimulus. As prestimulus duration is increased and, consequently, the two transients become more separated in time, their effects upon the reflex may become progressively more independent. The discrepancy between the PS effects upon eyeblink and HR in the elderly is probably due to a decline in HR response plasticity rather than central nervous system processes involved in reflex inhibit

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1983.tb00926.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTA between‐groups design (N = 75) was employed to investigate the effects of stimulus intensity and repetition on cardiovascular activity. It was predicted that as intensity increased, the pattern of physiological activity would change, indicating a transition from the orienting to the defense reflex. Cardiovascular activity was represented by measures of heart rate, digital pulse amplitude, and cephalic blood content. Subjects received 12 presentations of a 1000 Hz tone of 45, 60, 75, 90, or 105 dB. Stimulus risetime was 30 msec and the duration 2 sec. Analyses of variance revealed reliable effects of intensity and repetition on all cardiovascular variables. However, neither these results nor additional multivariate analyses supported the differentiation of orienting and defense reflexes as suggested by Sokolov (1963) or Graham (1979). The importance of the startle reflex in the interpretation of these findings was discusse

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1983.tb00927.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1983.tb00928.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThe present study investigated the role of attentional resources in the performance of controlled and automatic detection tasks. The amplitude of the P300 component of the event‐related potential has been shown to be a sensitive index of the attentional resources allocated to the perceptual processing of sensory stimuli. We found that P300s elicited in both automatic and controlled detection were large and of comparable amplitude, suggesting the involvement of a limited‐capacity mechanism in both tasks. This result is in agreement with previous behavioral studies showing equivalent dual‐task trade‐offs with both search tasks (Hoffman&Nelson, Note 1). In contrast, P300 latency was considerably reduced in the automatic task, suggesting that the main effect of practice in the detection task is to improve the discriminability of targets and dist

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1983.tb00929.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTTwo visual cliff experiments with human infants are reported that were designed to determine relationships among cardiac responses, avoidance and other behavioral responses, and developmental factors. The developmental factors considered were age at crawling onset, age at testing, and amount of crawling experience. In Experiment 1, infants were given either 30 or 60 days of crawling experience following crawling onset. In Experiment 2, infants were tested at either 9 or 12 months of age and crawling onset age was recorded. Infants were tested using a crawling avoidance procedure and the placing procedure that has been established for heart rate responses. Crawling onset age was the best predictor of avoidance behavior. Heart rate response was also a significant predictor of visual cliff avoidance, and was found to be related to testing age, especially for late crawlers. Looking down behavior was also found to distinguish crawling avoidance and crossing of the deep side of the cliff apparatus. These results, it is argued, suggest that fear is not the primary determinant of avoidance behavior on the visual cliff, but does contribute to avoidance at later ages.

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1983.tb00930.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1983.tb00931.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTThirty young male volunteers participated in a study of sustained continuous performance using a variety of computer‐based tasks. After 6 hrs of recorded sleep, 10 subjects were assigned to perform continuously for 42 hrs without break. Three of these subjects were unable to complete the 42‐hr assignment, and 8 of the 10 suffered psychological events such as hallucinations and disorientation. Ten subjects permitted six 1‐hr naps over the 42 hrs performed more successfully than those allowed no sleep. Ten subjects permitted one 6‐hr rest period performed best of all. Fatigue effects appeared after 6 hrs. Time‐of‐day (circadian) effects were at times stronger t

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1983.tb00932.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTFurther investigation of a recent theoretical model positing the existence of mutually antagonistic appetitive versus aversive motivational systems was conducted by providing monetary incentives for 3 trials and then either with or without warning terminating the incentives for the last 2 trials. Two dependent measures‐heart rate and electrodermal activity–were employed to test the predictions that incentives would activate the appetitive system and produce heart rate acceleration, while unsignalled termination of incentives (frustrative nonreward) would activate the aversive system and produce relative electrodermal activity increases. An additional goal was to investigate the effects on heart rate of different magnitudes of incentive per response unit and varying the amount of work per response unit–two ways of achieving different total amounts per trial. The data showed a clear and graded heart rate response to varying the amount of work per response unit. These results were interpreted as consistent with the conclusion that the heart rate response is a function of the amount of incentive per unit of effort. In contrast to the clear effect on heart rate, the incentive manipulations had no observable effect on electrodermal activity. Conversely, electrodermal activity showed a clear response to frustrative nonreward, while heart rate was not affected. These results were interpreted as consistent with the notion of separate motivational systems mediating different behavioral ef

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1983.tb00933.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1983.tb00934.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACTAchilles tendon (T) reflexes were evoked simultaneously in both legs during a fixed foreperiod of 1 sec. Volunteers were instructed to react as quickly as possible by one of four responses (in blocks): a plantar flexion of the left or right foot and a flexion of the left or right index finger. Prior to a foot response one leg was always involved in the response, prior to a finger response neither leg. Reflexes were evoked at 13 different points in time, from 100 msec prior to the warning signal (WS) to 100 msec after the response signal (RS). Amplitudes were expressed in percentages of control (intertrial interval) reflex amplitudes. In all conditions, amplitudes in both legs reached a peak 100 msec after the WS. After this non‐selective increment, reflex amplitudes preceding a finger response decreased but remained larger than the baseline. Prior to a foot movement, amplitudes in uninvolved muscles remained larger than the baseline as well, whereas amplitudes in the involved muscle were no longer different from the baseline. This differential effect was independent of the response side. It was concluded that preparation for a response is characterized by a selective lack of activation in the reflex arc of the agonist, and a non‐selective activation of the uninvolved spinal motor structu

ISSN:0048-5772    

DOI:10.1111/j.1469-8986.1983.tb00935.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY