Responses to Message Source and Presentation Using Psychophysiology

Visual attention was assessed by measuring dwell time, which is the length of time participants spent on looking at the specific areas of interest (AOIs) collected in miliseconds. Dwell time values were collected for 18 messages, and aggregated to provide the average dwell time scores for each arm. This was done for each vaping status (current vapers and susceptible non-vapers). Higher dwell time scores indicate higher visual attention, indicating better message outcomes.

Heart rate values were collected in beats per minute (BPM) on a per-second basis during the presentation of each 18 distinct messages as well as during the immediately preceding black screen (baseline) for each message. Descriptive statistics were used to summarize changes in the BPM values during the message exposure period by comparing the BPM values collected during each message second to the BPM values collected during the immediately preceding baseline period. These change scores were then averaged across all messages within each study arm to generate a mean BPM value per condition, and this was done for each vaping status (current vapers and susceptible non-vapers). Lower BPM values reflect greater cognitive response, therefore indicate better message outcomes.

Galvanic Skin Response (GSR) values were recorded in microsiemens on a per-second basis during the presentation of each 18 distinct messages as well as during the immediately preceding black screen (baseline) for each message. Descriptive statistics were used to summarize changes in GSR values by comparing each message response to its preceding baseline period. These change scores were then averaged across all messages within each study arm to generate a mean GSR score per condition, and this was done for each vaping status group (current vapers and susceptible non-vapers). Higher GSR values reflect greater physiological arousal, and indicate better message outcomes.

Participants' self-reported vaping attitudes were measured by using a five-point bipolar scale using 7 subscale items assessing whether participants thought vaping was enjoyable, healthy, safe, fun, smart, cool, and attractive on a scale from 1 (negative attitudes) to 5 (positive attitudes). Items were summed and averaged to create a single composite score, and this was done for each arm for each vaping status. Higher scores indicate more positive e-cigarette attitudes, therefore worse outcomes.

Participants' vaping intentions was measured by using a 3 subscale items assessing participants' intentions to vape: soon/anytime during the next year/would use offered by one of their best friends, on a scale from 1 (Definitely not) to 5 (Definitely yes). Items were summed and averaged to create a single composite score. This was done for each vaping status (current vapers and susceptible non-vapers). Higher scores indicate greater vaping intentions, therefore indicating worse outcome.