The vascular orienting response and the law of initial values

Vascular responses following exposure to the experimental situation (a type orienting reflex) were evaluated in 6 male subjects. Bilateral skin temperature was recorded from the head and finger regions for the duration of the experimental session. The interaction of Location X Trial (p less than or equal to 0.002) showed reliable differences between the head and finger sites and the left and right forehead sites early in the session followed by differential rates of change during the session across sites. The results support the recent claim for the importance of the law of initial values in finger temperature research and extend the findings to multiple site comparisons in the absence of hemispheric task demands. The vascular orienting reflex to the experimental context may augment initial value differences among recording sites.