The research on which this thesis is based examined the effects of sense of control and intrinsic motivation on motivational structure and it determine whether these motivational variables can be experimentally manipulated. Four studies were conducted with social drinkers. The first one (N = 94, 44% males) was a questionnaire study, which examined the relationships between participants' sense of control and intrinsic motivation and their
adaptive motivational structure and alcohol consumption. The measures included were Personal Concerns Inventory (PCI), Shapiro Control Inventory (SCI), Lester's Helplessness Questionnaire, Alcohol Use Questionnaire (AUQ), Aspiration Index, and Self-Determination Scale. Results showed that sense of control and intrinsic motivation were positively correlated with adaptive motivation and negatively correlated with alcohol consumption. In addition, compared to participants whose maladaptive motivation, those with an adaptive motivational structure (a) were higher on positive and overall sense of control, (b) were lower on helplessness, and they (d) drank less alcohol.
Mediational analyses revealed that adaptive motivational structure fully mediated of the relationship between sense of control/intrinsic motivation and alcohol consumption. The
second study (N = 106; 48% males) tested the effects of experimental manipulations of sense of control and intrinsic motivation on task-specific adaptive motivation, cognitive
performance, and implicit and explicit urges to drink. The experimental manipulation used anagrams and a modified, computerized version of Hiroto and Seligman's (1975) Concept-Training Cards. The manipulation techniques included enhancement information (i.e., choice, knowledge, feedback) and goal setting. The measures included task-specific versions of the Personal Concern Inventory (TSPCI), Shapiro Control Inventory (TSSCI), Intrinsic Motivation Inventory (IMI), Urges to Drink Questionnaire, and alcohol-Stroop test. In addition, participants' accuracy and speed of cognitive performance were measured with computerized verbal puzzles and memory quizzes. Participants were randomly assigned to either the No-Intervention Group, Low-Sense-of-Control Group, or High-Sense-of-Control Group. Results showed that the groups differed from one another on none of the measures at the pre-test. The post-experimental results showed that high and low levels of sense of control were successfully induced in the different the experimental groups. Moreover, compared to the No-Intervention Group and High-Sense-of-Control Group, the Low-Sense-of-Control Group (a) performed poorer on the cognitive tasks; (b) had less adaptive motivation; and ( c) were higher on explicit and implicit measures of urges to drink. Moreover, in terms of improvements on sense of control and intrinsic and adaptive motivation the groups were ordered as follows: High-Sense-of-Control Group> No-Intervention Group> Low-Sense-of-Control Group.
However, on explicit and implicit measures of urges to drink, the order of the groups was reversed. Study Three (N = 144, 38% males) tested the relative and combined effects of enhancement information and goal setting on participants' task-specific adaptive motivation. The design was a 2 x 2 factorial that included pre- and post-test measures, including the TSPCI, TSSCI and TSIMI. The experimental manipulation was the same as the one used in the second study. The results showed that the greatest increase in adaptive motivation resulted from the combined technique and the order of the groups on the post-test was: Combination Group (enhancement information and goal-setting) >Information Group> Goal-Setting Group> No-Intervention Group. In addition, a 45-day follow-up assessment showed that the Combination Group's task-specific adaptive
motivation continue to increase after the post-experimental assessment. The fourth study (N= 75, 47% males) tested the influence of mood induction on participants' task-specific
motivational structure. Measures included the TSPCI and the Positive Affect and Negative Affect Scale (PANAS) administered at pre- and post-test. Prior to the mood induction, which included music and Bos's technique, participants completed anagrams
and tasks with the Concept-Training Cards but without a motivational manipulation (i.e., no choice, no information, no feedback, and no goal setting). The results showed that on the pre-test, the groups differed from one another on none of the measures. The post-experimental results showed that a happy or a sad mood was successfully induced in the two experimental groups. On the post-test, none of the groups had changed from the pre-test on task-specific adaptive motivation. Possible applications of the results of the studies for future research and practice are discussed.