Cardiac orienting responses of 6- and 16-week-old infants

Since previous data suggested that the magnitude of orienting evidenced by cardiac deceleration increased over the first 16 weeks of life, 6- and 16-week-old infants were compared on various characteristics of orienting: habituation, dishabituation, and magnitude of deceleration to stimulus offset as well as to stimulus onset. Neither the change in stimulus following habituation trials nor the stimulus offset produced a large enough response to confidently evaluate age differences suggested by the data. Stimulus onset elicited a pronounced deceleration which for the two age groups was of equivalent magnitude on initial trials and declined similarly with stimulus repetition. It was suggested that similarity of the two age groups on these parameters was due to control of state within a narrow alert range, and that, in general, younger infants are less likely than older infants to show orienting when conditions for orienting are marginal.     

Heart-rate and electrodermal orienting responses to visual stimuli differing in complexity

Orienting response (OR) theory predicts that amount of information in the stimulus, or stimulus complexity, should be an important determinant of OR elicitation and habituation, more intense and more slowly habituating ORs being expected to complex than to simple stimuli. This prediction was tested in an experiment where subjects were exposed to simple and complex visual stimuli in randomized order, while heart-rate and skin conductance were measured. Complex stimuli evoked a more pronounced deceleratory heartrate response than did simple stimuli. However, the two conditions did not differ in rate of habituation of this response. For skin conductance responses, on the other hand, the complex stimulus took more trials than the simple stimulus to reach habituation, whereas the two conditions did not differ in response magnitude. Thus, the hypothesis of more intense orienting to complex stimuli was supported by the heart-rate data, and that of slower habituation to complex stimuli, of the skin conductance data.     

Stimulus significance effects in habituation of the phasic and tonic orienting reflex

Phasic and tonic measures of electrodermal activity were examined in a simple habituation paradigm, using innocuous visual stimuli. Separate groups were used to investigate the effects of stimulus significance, as manipulated by instructions. One group had no stimulus-related task (indifferent group), while the other was asked to silently count the stimuli to report to the experimenter later (significant group). Prestimulus skin conductance levels were considered as measures of the arousal level at each stimulus presentation, and the subsequent electrodermal responses were taken as the phasic orienting reflex (OR) elicited by each stimulus. Changes in prestimulus arousal were taken as measures of the tonic OR to the experimental series. Marked group differences were found in both phasic and tonic components of the OR. Some, but not all, of the significance effects in the phasic OR were attributable to differences in arousal. The results are discussed in the context of theoretical accounts of the OR.     

Extraversion and neuroticism in orienting reflex dishabituation

The present study examined the effects of extraversion (E) and neuroticism (N) as individual difference dimensions and of stimulus intensity on electrodermal orienting response habituation, test response, and dishabituation. Subjects were 162 college students selected from a screening sample of 860 as representing extreme groups of high, medium, and low E crossing with high, medium, and low N. Subjects in all nine resulting groups were habituated to criterion on auditory stimuli of 60, 80, and 100 db. A novel (test) stimulus and a dishabituating standard stimulus followed criteron habituation at each intensity. Results indicated that response amplitude for initial, test, and dishabituation responses was a direct function and that habituation rate (trials-to-criterion) was an inverse function of stimulus intensity. Extraverts habituated more rapidly than introverts at high intensity and gave smaller test and dishabituation responses. Some results differed when regression coefficients defined habituation rate and when first stimulus intensities alone were examined. Correlations among initial, test, and dishabituation responses and between each of these and the two measures of habituation rate are also reported. Results were interpreted as partially supportive of Eysenck's theory.     

Cardiac deceleration in newborns: habituation, dishabituation, and offset responses.

Twenty healthy, 1–4 day-old infants were selected from a sample of 135 neonates on the basis of alertness during testing. The infants were presented mild intensity colored light with gradual onset and offset while heart rate was monitored. Half the infants received six exposures to blue light followed by two exposures to blue-green light, whereas remaining subjects received colors in reverse order. Stimulus duration was 20 sec and variable periods between stimuli averaged 30 sec. Results of trend analysis of variance of the second-by-second cardiac data indicated that for infants older than the median age, the decelerative responses to both stimulus onset and offset were significant. Further, these subjects' onset decelerations significantly habituated within the six stimulus repetitions and significantly dishabituated with change in the stimulus color. Offset decelerations incremented over habituation trials and decremented with change in stimulus color. Responses of younger subjects were more variable which probably reflects their less complete recovery from the effects of maternal medication and the birth process.     

Age-related differences in lexical access, spreading activation, and simple pronunciation

An experiment was conducted to address age-related differences in lexical access, spreading activation, and pronunciation. Both young and older adults participated in a delayed pronunciation task to trace the time course of lexical access and a semantic priming task to trace the time course of spreading activation. In the delayed pronunciation task, subjects were presented a word and then, after varying delays, were presented a cue to pronounce the word aloud. Older adults benefited considerably more from the preexposure to the word than did the younger adults, suggesting an age-related difference in lexical access time. In the semantic priming pronunciation task, semantic relatedness (related vs. neutral), strength of the relationship (high vs. low), and prime-target stimulus onset asynchrony (200 ms, 350 ms, 500 ms, 650 ms, and 800 ms) were factorially crossed with age to investigate age-related differences in the buildup of semantic activation across time. The results from this task indicated that the activation pattern of the older adults closely mimicked that of the younger adults. Finally, the results of both tasks indicated that older adults were slower at both their onset to pronounce and their actual production durations (i.e., from onset to offset) in the pronunciation task. The results were interpreted as suggesting that input and output processes are slowed with age, but that the basic retrieval mechanism of spreading activation is spared by age.     

Psychophysiological and behavioral differences as a function of age and Parkinson’s disease

Differences related to age and to specific neurological (Parkinsonian) damage were studied by contrasting, respectively, old (mean age 64 years) and young (27 years) subjects (N=15), and old-normal (N=15) and old-Parkinsonian (N=15) subjects. Both behavioral as well as psychophysiological dependent variables were employed. The behavioral measure was performance on a discrimination learning task, while the psychophysiological measures were based on habituation to a repeated tone stimulus and on a Pavlovian differential conditioning preparation. The behavioral task showed predominantly age-related differences, with the young learning faster. Another age-related difference was interpreted as showing a more insight-like learning process in the young. Response-bias (beta) values did not differ between groups. Age-related differences also emerged more clearly than specific-neurological-damage differences in the psychophysiological data. The older subjects manifested markedly less autonomic conditioning, which was probably due to a lowering of reactivity, as well as the emergence of habituation to the (loud-noise) unconditional stimulus. A correlational analysis of discrimination conditioning also yielded age-related differences. Most notably, reactivity played a greater role in conditioning in the old than in the young subjects. The results illustrated how psychophysiological measures can provide information that complements those provided by behavioral measures.     

Exploring the mechanism of dishabituation

In this study we explored elicitation and habituation of the orienting reflex (OR) in the context of indifferent and significant stimuli, particularly aiming to clarify the mechanism driving dishabituation. An in-depth analysis of the mechanisms of electrodermal habituation and dishabituation was conducted, focusing on the role of state measures as determinants of the phasic response profile. Twenty-four young adult participants completed an auditory dishabituation task while electrodermal activity was recorded. Participants listened to a series of 10 innocuous tones of the same frequency (standards), followed by a deviant tone of a different frequency, and succeeded by 2-4 tones of the same frequency as the initial 10 stimuli. All stimuli had a random stimulus onset asynchrony of 5-7 s. Participants completed an indifferent condition in which there was no task in relation to the stimuli, and a significant condition where instruction was given to count the stimuli silently; order was counterbalanced between participants. As predicted, both skin conductance responses (SCRs) and skin conductance levels (SCLs) were larger for the significant than the indifferent condition. The initial phasic ORs were dependent on pre-stimulus arousal level, and there were significant decreases in both SCR and SCL over the first 10 standards in both conditions. Phasic response recovery was apparent to the deviant stimulus, and dishabituation to the following standard stimulus; both effects were enhanced in the significant condition. Sensitisation was apparent in SCL following the initial and deviant stimuli, but the extent of this was confounded with incomplete resolution of the preceding phasic OR in the significant condition. In the indifferent condition, dishabituation was independent of deviant-related sensitisation; this could not be tested in the significant condition. These findings suggest that dishabituation is not a process of sensitisation, but rather, a disruption of the habituation process.     

Paired comparison scaling of reaction potential from simultaneous measurements of GSR and looking time

Thurstone’s method of scaling from paired comparison data was employed to obtain estimates of reaction potential on eight successive presentations of randomly generated polygons. One set of scale values was based upon the magnitude of the GSR made by each of 40 Ss to the onset of each stimulus. Another set of scale values was based upon the Ss looking times, when the S was instructed to press a switch to terminate the stimulus after he finished looking at it. Following termination of each stimulus, a 20-sec period of no stimulation intervened prior to the next stimulus. The GSR reduced in size from trial to trial, describing a typical habituation curve, while looking time increased from trial to trial. Across trials the two sets of scale values were significantly negatively correlated (r=?0.91). The failure to find habituation of looking time was explained on the assumption that the 20-sec period between stimuli was noxious to the Ss, which resulted in longer and longer looking times across trials. These results were interpreted as indicating that habituation of the GSR is not merely a matter of reduced attention in the cognitive sense. In addition, it was pointed out that the use of orienting reflex concepts in dealing with attentional and other cognitive phenomena may be unjustified.     

Stimulus Significance Effects in Habituation of the Phasic and Tonic Orienting Reflex

Phasic and tonic measures of electrodermal activity were examined in a simple habituation paradigm, using innocuous visual stimuli. Separate groups were used to investigate the effects of stimulus significance, as manipulated by instructions. One group had no stimulus-related task (indifferent group), while the other was asked to silently count the stimuli to report to the experimenter later (significant group). Prestimulus skin conductance levels were considered as measures of the arousal level at each stimulus presentation, and the subsequent electrodermal responses were taken as the phasic orienting reflex (OR) elicited by each stimulus. Changes in prestimulus arousal were taken as measures of the tonic OR to the experimental series. Marked group differences were found in both phasic and tonic components of the OR. Some, but not all, of the significance effects in the phasic OR were attributable to differences in arousal. The results are discussed in the context of theoretical accounts of the OR.     

Habituation of orienting reaction in night terrors

A polygraphic study on resistance to habituation of the somatic (EMG), autonomic (finger vasoconstriction, galvanic skin reaction, respiration, pulse) and EEG (acoustic-evoked potential, EEG-blocking reaction) components of the orienting reaction elicited by a repetitive auditory stimulus was performed in 36 patients with night terrors and in 72 matched subjects in two control groups. The study evidenced a significantly higher resistance to habituation of the orienting reaction in patients with night terrors than in normal subjects (control group I) but significantly lower than in patients with symptomatic epilepsy (control group II). The severity of these habituation disturbances in patients with night terrors depended on the patients’ age, the history of nocturnal events and their clinical form, as well as on the etiology of episodes. The habituation changes found in patients with night terrors may be ascribed to the nervous disorders of functional and/or organic nature which generated also the night terrors episodes.     

Orienting reaction habituation in chronic alcoholics

A polygraphic study on resistance to habituation of the somatic (EMG), autonomic (finger plethysmogram, galvanic skin reaction, respiration) and EEG (acoustic-evoked potential and EEG-blocking reaction) components of the orienting reaction elicited by a repetitive auditory stimulus was performed in 67 chronic alcoholics and in 70 matched normal subjects (control group). The study showed a significantly lower resistance to habituation of the orienting reaction in alcoholics than in normal control subjects. The severity of this habituation disturbance depended on the patients’ age, type of alcoholism, alcohol consumption intensity and chronicity, as well as the type of resting EEG.     

Effects of stimulus duration and intensity on the rate and specificity of behavioural habituation

Tone stimuli were presented to rats once per day until habituation was reached. Neither the duration nor the intensity of the stimulus affected the rate of habituation. Habituation was specific to both these stimulus parameters as shown by the distraction produced by either an increase or a decrease in the original stimulus value. It is suggested that some of the discrepancies in the literature might be resolved if a distinction is drawn between habituation of orienting responses and the decrement of more specific responses.     

Retention of orienting reaction habituation in chronic alcoholics

A polygraphic study on resistance to habituation of the somatic (EMG), autonomic (finger plethysmogram, galvanic skin reaction, respiration) and EEG (acoustic-evoked potential and EEG-blocking reaction) components of the orienting reaction, elicited by a repetitive auditory stimulus during successive (weekly) sessions was performed in 67 chronic alcoholics and in 70 matched normal subjects (control group). The study showed significant retention disturbances of orienting reaction habituation (i.e., of learning), or the “saving” of stimulations, achieved from one session to the other to obtain the habituation criterion, the savings being less in alcoholics than in control subjects. The severity of habituation retention disturbances depended on patients’ ages, types of alcoholism, alcohol consumption intensity and chronicity, as well as the type of resting EEG.     

Age differences in within-session habituation of exploratory behavior: effects of stimulus complexity

The effects of age on the habituation of exploratory behavior of 8-month- and 28-month-old male C57BL/NNia mice were examined under three different stimulus complexity conditions. Increases in the degree of stimulus complexity resulted in an attenuation of between-session habituation and an initial disruption of within-session habituation by 8-month-old mice. Although increases in stimulus complexity also resulted in an increase in the overall level of exploration by aged mice, stimulus complexity was not found to have a systematic effect on between- or within-session habituation by aged mice. No between-session habituation was observed in aged mice under any of the stimulus complexity conditions. Further, aged mice exhibited significant within-session increases, rather than decreases, in exploration under each stimulus complexity condition. This disruption of within-session habituation in aged mice was found to persist over four daily test sessions. In view of the specific patterns of exploration by aged mice, the disruption of within-session habituation was attributed to age-related differences in reactivity to the arousal-inducing properties of novel stimuli.     

Visual and auditory orienting responses in preterm infants: a comparison of three cohorts over time.

Visual and auditory orienting responses were compared in three cohorts of preterm infants (N = 351) born between 1977 and 1987. The infants were divided into one group born between 25 and 34 weeks gestational age (n = 140) and one group born between 35 and 37 weeks gestational age (n = 211). Ratings were made of the infants' best orienting responses to a bull's-eye, rattle, bell, voice, and face plus voice combined. Analyses of covariance were computed to adjust for changes in perinatal variables between 1977 and 1987. For both groups, there were significant differences between cohorts on orienting to the bull's-eye, with a trend for the 25- to 34-week group on orienting to the rattle. Behavioral outcome for preterm infants has improved with changes in neonatal intensive care.     

Orienting and humor responses: A synthesis

Evidence is presented for a hypothesis that a humor response is an instance of a more general orienting response. The two responses both occur to stimulus novelty or incongruity and are identical behaviorally and physiologically, althouth their subjective components may differ. Evidence for the hypothesis is based on a series of paremeters that affect orienting and humor responses identically. Parameters on which the responses show strong parallels are the effects of habituation and the degree of stimulus change. Weaker parallels exist for such parameters as direction of stimulus change, number of habituation trials, stimulus complexity, salience, intensity, and the subject's arousal level. The weaker parallels are also areas in which additional humor research is needed.     

Cortical evoked potentials as indicators of auditory-visual cross-modal association in young adults

Auditory evoked potentials (AEPs) were studied from scalp locations Cz and Oz on 37 adults aged 20–22 years during sensori-sensorial association of a weak sound (S) and a strong flash of light (L). After sound alone repetition (habituation), S-L association modified AEP: first, it caused a generalized orienting response expressed as increasing of Cz and Oz amplitude AEPs. Then, this pattern gave way to an activation limited to the Oz lead: the increase of amplitude was then concomitant with shortened latencies when compared to sound-alone-habituated responses. Inter-individual differences were observed since these occipital modifications were recorded only on 26 subjects. The other 11 subjects did not exhibit any occipital modifications following S-L association. For them, the main modification was a strong decrease of Cz AEP induced by S-L association. These two groups also differed in their capacity to ignore irrelevent stimuli which is higher in the first group (AEP amplitude habituation with sound-alone repetition) than in the second one (no AEP habituation).     

Overextinction of the orienting reaction

Sokolov’s 1963 report of return of the orienting reaction (OR) to repeated stimulus presentations following habituation was examined in 18 S’s using the galvanic skin response (GSR) component of the OR and an auditory stimulus of 60 db intensity and 1000 cps. Both group and individual S data analysis indicated a return of the OR which habituated quickly. The number of stimulus presentations to the OR return point showed an inverse relationship to rate of initial OR habituation for individual S’s.     

Effects of pentobarbital sodium anesthesia and neurohumoral agents on the cardiac orienting reflex

Studies of the cardiac orienting reflex in 16 dogs, moderately anesthetized and awake are reported. In the anesthetized dogs prominent transient heart rate decrease was commonly noted within one or two beats after the onset of various auditory stimuli, and less often after visual stimuli. This cardiac inhibition was neither as prominent nor as frequent in occurrence in awake dogs. The respiratory cycle at stimulus onset influenced the appearance and degree of heart rate decrease, with the greatest and most frequent decreases occurring during the expiratory phase. Atropine abolished the response. There was little evidence of habituation of this orienting response under anesthesia, although “waxing” and “waning” apparently related to minute-by-minute fluctuations in degree of unconsciousness, occurred. These findings are discussed in relation to neurophysiological and neuroanatomical correlates of orienting responses, hypotheses of orienting and attention and cardiovascular neurohumoral mediators.