There are clear sex differences in incidence of phobias for small animals, and in questionnaire-measured fear for animals. The present study examined whether these sex differences were reflected also in electrodermal conditioning to potentially phobic stimuli. Separate groups of males and females were exposed to a conditioning session involving either potentially phobic, snakes and spiders, or fear-irrelevant, flowers and mushrooms, conditioned stimuli with electric shock as the unconditioned stimulus. A long interstimulus interval differential paradigm was used, allowing analysis of first- and second interval anticipatory responses, and third-interval omission responses. There were 8 habituation trials, 16 acquisition trials and 40 extinction trials. Half of the trials involved the reinforced cue, and the other half the unreinforced cue. There were clear conditioning effects, with superior acquisition and resistance to extinction to the phobic as compared to the fear-irrelevant stimuli. However, there were no differences between the two sexes. The results were interpreted in terms of the preparedness theory of phobias, and in terms of social learning factors.

Adult↗

PubMed1976

The premise of equipotentiality in human classical conditioning: conditioned electrodermal responses to potentially phobic stimuli.

The premise of equipotentiality, which has been widely adhered to among learning theorists, states that the laws of learning should not vary with the use of particular stimuli, responses, or reinforcements. This premise has recently been challenged by some data originating within the learning tradition itself, for example, studies on the effects of verbal stimuli in eye-lid conditioning. More importantly, however, the premise of equipotentiality is incompatible with data from experiments carried out within a biological-ethological framework. The results of such studies indicate that a given species is prepared to associate certain stimuli, responses, and reinforcers but not others. In an attempt to examine the validity of this premise in human classical conditioning, we investigated the effect of pictures of potentially phobic objects as conditioned stimuli (CSs) for electrodermal responses, since it has been suggested that phobias may be instances of biologically prepared learning. Three experiments are reported, all of them involving a long interstimulus interval differential conditioning paradigm with different pictures as CSs and electric shock as the unconditioned stimulus (UCS). In Experiment 1 we established that different pictures are differentially effective as CSs. A groupconditioned to potentially phobic stimuli, snakes or spiders, showed greater resistance to extinction than a group conditioned to fear-irrelevant pictorial stimuli, that is, flowers or mushrooms. A third group conditioned to "representative laboratory stimuli," circles or triangles, fell in between thses two groups. Experuce similar effects to those observed with phobic and fear-irrelevant stimuli in Experiment 1. In Experiment 3 superior resistance to extinction for phobic stimuli was demonstrated when the UCS was an electric shock, but not when it was a tone to which the subject produced reaction times. Thus, the effect appears specific for aversive UCSs, and CS-UCS "belongingness" has been demonstrated. It was concluded that our data do challenge the premise of equipotentiality in human conditioning. There are several learning-theory accounts that could accommodate at least some aspects of the data, but they seem to be best explained in terms of biologically orsiented constructs, such as preparedness.

Acoustic Stimulation↗

PubMedDate not supplied

Pavlovian extinction, phobias, and the limits of the cognitive paradigm.

The slow or total lack of decrease in some autonomic responses during extinction in aversive conditioning and concomitant verbalization of fear have remained a problem for learning theories and psychophysiology. Removal of the aversive stimulus should result in a rapid decrement in responding, as it does in cognitive and somatic systems. In laboratory analogues of phobia and clinical neurosis, however, such decreases do not occur in some autonomic responses and reported fear. In this article three areas of research are presented in which dissociations occur between cognitive and autonomic responses: 1) relational learning, 2) phobia, and 3) incubation. The data indicate that there are some important distinctions to be made concerning the properties of different psychological and physiological systems. These distinctions pertain to the differences between cognitive and noncognitive systems, between the two branches of the ANS, and between acquisition and extinction processes. These distinctions lead to a number of hypotheses concerning dissociations between response systems and have important implications for the understanding and treatment of neurosis.

Autonomic Nervous System↗

PubMedDate not supplied

Haemodynamic and electrodermal correlates of psychogenic stimuli in hypertensive and normotensive subjects.

This study compared tonic and phasic cardiovascular and electrodermal activity in subjects having essential arterial hypertension (HT) with that of sex- and age-matched normotensive (NT) controls. Fourteen subjects of each group were subjected to 'sensory intake' (letter identification) and 'rejection' (mental arithmetic) tasks while recordings were made of: systolic and diastolic arterial blood pressure, hand and forearm blood flows, heart rate, skin conductance level and fluctuations. The rejection task affected more physiological variables in both groups than the intake task did. The reaction pattern was similar in both groups. Except for systolic and diastolic blood pressures tonic cardiovascular and electrodermal activity of the HT group was not different from that of the NT group. The same pattern, although less clear cut, was observed when reactivity was studied. According to analyses based on pressure levels both tasks raised the systolic blood pressure of the HT group, whereas only the rejection task raised systolic blood pressure in the NT group. In contrast, an analyses based on blood pressure changes from base to task indicated that both groups increased systolic blood pressure to both tasks. Since virtually no other differences in reactivity were found, this study offers weak support for the notion that subjects having essential arterial hypertension are pressor hyper-reactors.

Adult↗

PubMedDate not supplied

Cortisol excretion during the defense reaction in humans.

Twelve subjects with specific phobias were exposed to slides with a phobic or a neutral content while cortisol excretion, electrodermal activity, and distress-ratings were studied. Six subjects fearful of blood and mutilation, and six of snakes or spiders, were presented with two sets of ten different slides (phobic or neutral; 8-sec exposures, separated by 50-sec intervals) with the order of presentation balanced between days. Before and after each session, subjects rated feelings of distress, and urine samples were obtained for the determination of cortisol by radioimmunoassay. Electrodermal activity was recorded before and during slide presentation. Compared to neutral exposures, phobic slides elicited larger cortisol excretion, higher distress ratings, and greater skin-conductance responses with slower recovery. No differences between animal and blood and mutilation phobics were observed. Thus, humans having specific phobias exhibit pituitary-adrenal cortical arousal during the defense reaction elicited by slides of their phobic objects.

Adult↗

PubMedDate not supplied

Effects of exercise training on cardiovascular function and plasma lipid, lipoprotein, and apolipoprotein concentrations in premenopausal and postmenopausal women.

This study examined the effects of aerobic exercise on lipid levels in premenopausal and postmenopausal women. Fifty healthy middle-aged women (mean age, 50 years) were randomly assigned to 12 weeks of either aerobic exercise (walking and jogging) or nonaerobic strength exercise (circuit Nautilus training). Concentrations of total cholesterol, high density lipoprotein cholesterol, low density lipoprotein cholesterol, and very low density lipoprotein cholesterol were assessed, along with apolipoprotein (apo) A-I, apo A-II, apo B, and triglycerides. To document changes in aerobic capacity, maximum treadmill testing was performed with expired-gas analysis before and after the exercise program. Aerobic exercise was associated with an 18% improvement in peak VO2. Women in the aerobic group had an increased VO2, from 26.7 to 31.4 ml/kg/min (p less than 0.0001), while the VO2 of the women in the strength training group did not change (25.8 ml/kg/min before and after). There were no differential changes in lipid levels because all subjects experienced slight reductions in high density lipoprotein cholesterol and total cholesterol and increases in apo A-I and the apo A-I to apo B ratio. There was a tendency for the aerobic group to exhibit lower levels of apo A-II and a greater apo A-I to apo A-II ratio, however. We conclude that premenopausal and postmenopausal women experience similar changes in aerobic capacity and lipid levels with exercise and that the short-term effects of aerobic and nonaerobic exercise on lipid profiles are generally comparable.

Analysis of Variance↗

PubMedDate not supplied

Previous medical history and medications as risk factors for hairy cell leukaemia.

To investigate the possible role of previous medical history and previous medications as risk factors for hairy cell leukaemia (HCL) we performed a population based case-control study on 121 male HCL patients and 484 controls. The data were collected through a self-administered mailed questionnaire. Elevated odds ratios (OR) were found for a history of appendicitis [OR 1.9; 95% confidence interval (CI) 0.9-4.2] and pneumonia (OR 2.9; CI 0.9-9.6). We found a reduced risk for HCL associated with a history of myocardial infarction (OR 0.3; CI 0.4-2.5), hypertension (OR 0.6; CI 0.3-1.2) and thromboembolic disease (OR 0.6; CI 0.1-2.7). Reduced OR was also associated to a history of diabetes mellitus (OR 0.6; CI 0.1-2.9) and a diagnosis of hyperlipidemia (OR 0.8; CI 0.2-3.6). HCL is an indolent disease with a clinical course of many years and it can not be excluded that the disease leads to metabolic changes, resulting in a changed risk for these diagnoses. When the role of previous medications were investigated, increased OR was found for NSAID (OR 3.4; CI 1.1-10.2). Decreased OR was found for the anti-coagulative agent warfarin (OR 0.4; CI 0.1-1.5). A history of a previous malignancy preceeding the diagnosis of HCL as reported to the Swedish Cancer Registry yielded an increased OR of 3.2 (CI 1.2-8.5). All results must be interpreted with caution, as there is a possibility of misclassification. Medications is difficults to remember, particularly several years after consumption. As many comparisons were made, there is always a possibility of correlations occuring by chance.

Appendicitis↗