Internal consistency and temporal stability of classically conditioned skin conductance responses.

The reliability of classically conditioned skin conductance responses was investigated. Temporal stability was determined in 28 subjects studied three weeks apart (study 1), and internal consistency in 223 subjects studied once (study 2). A discriminative classical conditioning paradigm using slides with a duration of 8 s served as conditioned stimuli (CS) for an aversive unconditioned noise stimulus (study 1) or a mild unconditioned electric shock stimulus (UCS) (study 2). Electrodermal responses were recorded during a habituation phase (4 trials), an acquisition phase, where CS+ was paired repeatedly with the UCS, while CS- never was (8 trials), and an extinction phase during which shocks were withheld (8 trials each). First interval responses were measured 1-4 s after CS- onset during all phases of the experiment. During the acquisition and extinction phases, second interval responses were scored 5-9 s after CS- onset while third interval responses were determined 1-4 s after CS- termination. Internal consistency was significant for the first (rxy range 0.96-0.90), second (rxy range 0.84-0.54) and third (rxy range 0.96-0.86) skin conductance interval response. Temporal stability was highest for the first interval response (rxy range 0.72-0.37) and lowest for the second interval response (rxy range 0.51-0.05). It is concluded that the first interval skin conductance response shows adequate internal consistency and temporal stability to assess individual differences in classical conditioning.

Cardiovascular responses to psychological and physiological stressors during the menstrual cycle.

Psychological and physical stress reactivity was studied in 15 females in two phases of the menstrual cycle (cycle days 5-7 and 24-26) and in 15 males. Each female was matched for age and time between sessions with a male. There was a significant phase-related difference in cardiovascular reactivity among the females. Females in the luteal phase reacted significantly more to the cold pressor but not to the mental arithmetic test. There were significant sex differences in systolic blood pressure, the males displaying higher levels during provocation, as well as during control conditions. The females were more reactive in heart rate to the mental stressor when changes from control conditions to stress were calculated. When the data were analyzed separately for smokers and non-smokers, there was a significant interaction between menstrual cycle phase and smoking. In the luteal phase, the female smokers were more reactive in systolic blood pressure than the non-smokers. The male smokers were more reactive than the non-smokers in diastolic blood pressure response to mental arithmetic, but not to the cold pressor test. Significantly higher levels of cortisol and aldosterone were found in the luteal phase as compared with the follicular phase. The cortisol levels were higher in the males than in the females in the follicular phase, whereas the female aldosterone concentrations in the luteal phase were higher than those of the males.