Threshold assessment of attitude, subjective norm, and perceived behavioral control for predicting exercise intention and behavior

According to the theory of planned behavior (TPB), attitude, subjective norm, and perceived behavioral control (PBC) are hypothesized to have linear associations with intention and behavior. However, no previous research has examined this hypothesized linearity across scale responses. Further, no study using social cognitive measures has detailed the incremental increases in the proportion of people meeting the American College of Sports Medicine's (ACSM) exercise guidelines across scale responses. The purpose of this study was to examine mean scores of intention and behavior and detail the proportion of participants meeting ACSM's exercise guidelines for each TPB construct response category (i.e. 1-7). Participants were university undergraduates (N = 585) who completed measures of the TPB and a 2-week follow-up of exercise behavior. Results were evaluated using effect sizes (d, w) and p-levels, and provided general support for the linear effects of affective and instrumental attitude, but PBC and subjective norm were identified as having specific thresholds. Further, thresholds of positive, but not negative, exercise social cognition were identified for meeting ACSM's criteria with the exception of affective attitude. Threshold analysis was discussed as a novel way of analyzing TPB data by providing additional information about the expected success of intervention efforts focused on TPB constructs. (c) 2004 Elsevier Ltd. All rights reserved.