Examining Expectancy Challenges to Prevent Nonmedical Prescription Stimulant Use

Intention to engage in nonmedical prescription stimulant use in the following 6 months will be assessed as a proxy of incident of use, and used in analyses if incidence of use is low across all groups. This will be assessed via a 100mm Visual Analogue Scale (0-100). Higher scores indicate higher intention to engage in use.

The Caffeine Expectancy Questionnaire will be used to examine whether expectancy effects for caffeine were modified for the Caffeine-Based Expectancy Challenge group specifically. This measure includes 7 factors, though only Energy/work enhancement, social/mood enhancement, and anxiety/negative physical effects will be analyzed. Items are answered along a 6 point scale (0-5), and scores for each factor are averaged; higher scores indicate stronger expectancies.

The Comprehensive Effects of Alcohol Questionnaire will be used to examine whether expectancy effects for alcohol are modified over time; this is being utilized to ensure that the interventions had specific effects on prescription stimulants and caffeine, and not substance use in general. Positive and negative expectancies can be assessed with this measure, and scores are computed by averaging items loading onto each factor. Items are scored along a 4 point scale (0-3).

Changes in subjective mood and arousal will be assessed across laboratory visits (i.e., to examine whether expectation to receive Adderall and/or ingestion of 200mg caffeine affects subjective mood) using Visual Analogue Scales. Participants will complete scales for the following items: how well do they expect to perform, feeling good, feeling bad, feeling attentive, feeling focused, feeling high, feeling stimulated, feeling motivated, and amount of effort intended to put forth. Each item is measured along a 100mm scale (0-100), with higher scores indicating stronger subjective effects.

Changes in experienced drug effects will be assessed across laboratory visits (i.e., to examine whether expectation to receive Adderall and/or ingestion of 200mg caffeine affects experienced drug effects) via the Addiction Research Center Inventory. This measure includes 5 subscales: euphoria (scores range from 0-15), dysphoria (scores range from 0-14), intellectual energy and efficiency (scores range from 0-13), amphetamine effects (scores range from 0-11), and sedation (scores range from 0-15). Higher scores indicate stronger experienced drug effects in each domain.

The Conners' Continuous Performance Test III will be used to assess changes in attention, impulsivity, and vigilance across laboratory visits. T-scores are provided for each measure. T-scores between 45 and 69 indicate average performance, while scores outside of that range indicate performance difficulties.

The Selective Reminding Test is a measure of learning and memory to assess whether there are differences across laboratory visits. Number of words (out of 12) recalled across 6 trials are tallied for a measure of immediate memory (range: 0-72). Additionally, the number of words recalled across consecutive trials are measured as an index of movement into long term storage (with higher scores indicating better memory; range: 0-72). Long-term memory is also assessed (range: 0-12, with higher scores indicating better memory), as is recognition memory (range: 0-12, with higher scores indicating better memory).

The Paced Auditory Serial Addition Test will be used to assess differences in processing speed and divided attention across laboratory visits. This test includes 4 trials, each of which provides a total correct score out of 25. A total score is computed (0-100), with higher scores indicating better performance.

The Stroop Test will be used to assess differences in selective attention and processing speed across laboratory visits. This test provides reaction time scores for correct trials (smaller scores indicate better performance), as well as percentage of correct trials (out of 100%; higher scores indicate better performance).

The Letter-Number Sequencing test will be used to assess differences in working memory across laboratory visits. This test provides a total score correct (range: 0-30), with higher scores indicating better performance.

The Verbal Fluency test will be used to assess verbal fluency and information retrieval across laboratory visits. A total score correct is calculated (no maximum score), with higher scores indicating better performance.

The Symbol Search test will be used to assess processing speed across laboratory visits. A total score correct is calculated (range: 0-60), with higher scores indicating better performance.