Age differences in autonomic nervous system response patterns were investigated to determine if there was an age-related increase in the tendency to respond to multiple stimuli with a consistent response hierarchy (individual consistency). Five stimuli were administered in a Latin Square design-mental arithmetic, cold pressor. isometric exercise, comic slide, and time estimation. A warning tone was presented before each stimulus. Physiological measures included heart rate, systolic and diastotic blood pressures, skin potential, breathing rate, and digital blood flow. To compare responses in different systems, responses were standardized according to the formula, Z = |50 + 10 (X -M )]/a, where Z is the standardized score, X is the difference between stimulation and warning levels, M is the average response for that system, and a is the square root of the mean square for error from the analysis of variance computed for each response system. A matrix was generated for each subject which included his Z scores from the six response systems for the five stimuli. Intraclass correlations were then computed. Individual consistency significantly increased with increasing age (r= .33,p<.005).

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The effect of epidermal hydration on skin potential and conductance measurements was investigated in young and old men. The condition of least hydration used a 0.5% KCl glycol electrolyte. Two conditions used a 0.5% aqueous KCl electrolyte differing in that the most hydrated site received a 15‐min pretreatment of soaking in distilled water whereas the intermediate hydration site received no pretreatment. These hydration conditions were used in recording three channels of skin potential and three channels of skin conductance during three tasks: 1) tone presentations after rest, 2) simple reaction time, and 3) choice reaction time. There were no significant age differences in the effect of electrolyte on skin conductance level and response. There were age differences in the effect of electrolyte on skin potential level (SPL) and response (SPR). Young adult SPR was monotonically related to hydration with the largest response magnitude occurring with the least hydration. Electrolyte did not significantly affect SPR magnitude of the aged. For the young subjects, SPL was monotonically related to hydration with the most negative SPL occurring with the least hydration. For the aged subjects, the least negative SPL occurred in the condition of least hydration. We postulate that this reversal in the hydration/SPL relationship in old age reflects a reversal in the relative magnitudes of sweat gland and epidermal potentials: in old subjects the epidermal potential is greater than the sweat gland potential.

Age differences in skin potential level (SPL) of young adult and aged men were investigated using basal skin potential level (BSPL) procedures at three levels of epidermal hydration. A glycol medium was used at a site of least hydration. A distilled water and agar solution was the medium at two other more hydrated sites which also received either 0 min or 15 min pretreatment in distilled water. A 0.5% KCl electrolyte concentration was used at all sites. Significant effects for age and hydration were dependent on the point in the recording session comparisons were made. The major findings were: (1) the old men had significantly lower SPLs than did the young men at the start of recording with the glycol electrolyte medium; there were no significant age differences at the start of recording with the agar mediums, or at BSPL with any hydration condition. (2) Hydration significantly affected SPL magnitude at the start of recording, but not at BSPL. SPL recorded with the glycol medium at certain points in the recording was significantly related to outdoor activity among the aged men. This effect was independent of differences in cardiovascular status, and cardiovascular status was not significantly correlated with glycol SPL. It is concluded that there is a reduced sweat gland potential in old age which can only be observed when recording conditions produce high epidermal resistance. This reduced sweat gland potential is related to low levels of outdoor activity.

Two experiments comparing the skin potential level (SPL) of young (30 to 47 years), middle-aged (48 to 65 years), and old (66 to 82 years) men during rest and during stimulus presentations using a nonhydrating electrolyte medium demonstrated that there was an ordered relationship between SPL negativity and age with the older men having less negative levels. Age differences in SPL were dependent upon recording site with larger age differences occurring when SPL was recorded from the medial phalanx than when SPL was recorded from the thenar eminence.

The present study showed that researchers must consider underlying data structure when using hierarchical agglomerative cluster analysis to group jobs. Five cluster procedures were applied to four simulated data sets constructed to reflect common job analysis situations. The structures contained jobs varying in degree of task overlap, number of tasks performed, and relative number of people doing the jobs. Average linkage/distance was the most accurate procedure when jobs had highly positively correlated task profiles, a situation characteristic of jobs within a career family over a restricted range of levels. Average linkage/correlation was the most accurate for three other structures containing jobs whose profiles were not highly positively correlated. Such are characteristically found when analyzing (a) jobs in different functional units, (b) jobs over a wide range of hierarchical levels such as entry to advanced, and (c) jobs differing markedly in the number of incumbents.