Attention and verbalization: Differential responsivity of cardiovascular and electrodermal systems

Abstract

A recent study showed, (1) that changes in heart rate (HR) were indicators of a subject's attention: acceleratory HR corresponding to environmental rejection (thinking) and deceleratory HR to environmental intake; and (2) that skin conductance (SC) increased in both rejection and intake situations. These results were challenged by several authors who failed to find differential GSR and HR responding and who found some evidence to suggest that HR acceleration was an artifact of verbalization. In order to clarify these contradictory findings, the present study used constant stimuli for intake, rejection and verbalization conditions since the previous designs were confounded by the use of different stimuli for the various manipulations. GSR and HR were recorded from 48 male Ss who observed slides under four conditions: (1) looking at (INV: intake-no verbalization); (2) reading aloud (IV: intake-verbalization; (3) adding silently (RNV: rejection-verbalization); and (4) adding aloud (RV: rejection-verbalization). Each slide was presented for fifteen seconds and consisted of thirteen numbers arranged to elicit interest. The 48 Ss were divided into four groups of twelve with a Latin Square design utilized for presenting the four conditions (4 slides per condition) in four different orders. The analysis of the data showed that for both the SC and HR variables, responsivity differed among the four conditions. For the HR data, (1) the RV and IV conditions resulted in acceleratory changes with the RV change being greater; (2) the RNV condition resulted in virtually no change; and (3) the INV heart rate was deceleratory. The means for the amount of SC change and base HR paralleled those of the HR change with the RV condition demonstrating the greatest amount of change in SC and highest base HR, and the INV condition the smallest change in SC and the lowest base HR. Correlations among the HR changes scores across conditions showed that the changes for the INV conditions were independent of the changes for the other three conditions which were related to each other. Results of the study suggested (1) that HR changes are a function of an interaction between verbalization and attention, (2) that a modified concept of general arousal theory which posits separate arousal continuums for either situations resulting in HR acceleration or situations resulting in HR deceleration may explain previous contradictory findings and (3) that it may be profitable to classify Ss into categories of HR accelarators and HR decelerators.