Percolating ideas: The effects of caffeine on creative thinking and problem solving

Caffeine is the most widely consumed psychotropic drug in the world, with numerous studies documenting the effects of caffeine on people’s alertness, vigilance, mood, concentration, and attentional focus. The effects of caffeine on creative thinking, however, remain unknown. In a randomized placebo-controlled between-subject double-blind design the present study investigated the effect of moderate caffeine consumption on creative problem solving (i.e., convergent thinking) and creative idea generation (i.e., divergent thinking). We found that participants who consumed 200 mg of caffeine (approximately one 12 oz cup of coffee, n = 44), compared to those in the placebo condition (n = 44), showed significantly enhanced problem-solving abilities. Caffeine had no significant effects on creative generation or on working memory. The effects remained after controlling for participants’ caffeine expectancies, whether they believed they consumed caffeine or a placebo, and changes in mood. Possible mechanisms and future directions are discussed.     

Human coffee drinking: manipulation of concentration and caffeine dose.

In a residential research ward coffee drinking was studied in 9 volunteer human subjects with histories of heavy coffee drinking. A series of five experiments was undertaken to characterize adlibitum coffee consumption and to investigate the effects of manipulating coffee concentration, caffeine dose per cup, and caffeine preloads prior to coffee drinking. Manipulations were double-blind and scheduled in randomized sequences across days. When cups of coffee were freely available, coffee drinking tended to be rather regularly spaced during the day with intercup intervals becoming progressively longer throughout the day; experimental manipulations showed that this lengthening of intercup intervals was not due to accumulating caffeine levels. Number of cups of coffee consumed was an inverted U-shaped function of both coffee concentration and caffeine dose per cup; however, coffee-concentration and dose-per-cup manipulations did not produce similar effects on other measures of coffee drinking (intercup interval, time to drink a cup, within-day distribution of cups). Caffeine preload produced dose-related decreases in number of cups consumed. As a whole, these experiments provide some limited evidence for both the suppressive and the reinforcing effects of caffeine on coffee consumption. Examination of total daily coffee and caffeine intake across experiments, however, provides no evidence for precise regulation (i.e., titration) of coffee or caffeine intake.     

Caffeine consumption questionnaire: a standardized measure for caffeine consumption in undergraduate students

Undergraduate students (N=691) were given the 1992 Caffeine Consumption Questionnaire of Landrum and provided information on age, sex, and year in school. A subset (n = 168) of those completing the questionnaire were also given the Morningness-Eveningness Questionnaire of Horne and Ostberg. Analysis indicated that the average intake of caffeine was roughly 1,600 mg, i.e., a range from 13 mg to 21,840 mg per week. Older students consumed more caffeine than younger ones, and students with an Evening personality preference consumed more caffeine in the evening and nighttime hours than those with a Morning personality preference. These results are discussed in the context of other caffeine studies. Caffeine consumption is an important issue, and a consistent measurement system should be used by various researchers testing different populations.     

Measuring Outcome Expectancies for Specific Coping Behaviors: the Coping Expectancies Scale (CES)

Outcome expectancies for specific coping strategies may help explain why people vary in their choices of coping strategies (e.g., whether to smoke a cigarette or talk to a friend). These choices have relevance to both physical and mental health. The current study evaluated the psychometric properties of a new measure of mood regulation expectancies for specific explicit coping strategies, the Coping Expectancies Scale (CES). 552 adults completed the CES and other measures online. Factor analysis of the CES using Maximum Likelihood Extraction with promax rotation revealed three factors: Expectancies for Passive/Avoidant Coping, Expectancies for Active Behavioral Coping, and Expectancies for Active Cognitive Coping. Concurrent, discriminant, and predictive validity for these factors were strong, as was retest reliability. The CES enables researchers to measure expectancies for specific coping strategies, which may in turn help to explain people’s choices of strategies. In addition, the ability to measure these expectancies may allow for the development of treatment interventions that directly target them, ultimately enabling clients to adjust their expectancies and their choices of coping behavior, with implications for health and well-being.     

Effects of caffeine on performance of low intensity tasks

31 college age men and women who consume less than three caffeinated beverages per week agreed to participate as subjects in research on the effects of acute caffeine intake on low intensity task performance. All subjects performed two randomly administered test conditions: (1) caffeine (5 mg/kg) and (2) placebo on separate visits following an initial 1-hr. orientation visit. Subjects were administered the beverage 30 min. prior to performing 12 separate tests assessing basic mathematics, simple response, logical reasoning, hand-eye coordination, and spatial and assembly skills. The Spielberger State Anxiety test was administered immediately after consuming the test beverage and once again at posttest. Analysis showed that caffeine did not significantly affect performance on all tests with the exception of the peripheral awareness (hand-eye coordination) test on which performance was higher after ingesting caffeine. The placebo treatment produced no effect on state anxiety, which contrasted with a significant rise in anxiety after caffeine consumption. State anxiety values were significantly greater after caffeine treatment relative to the placebo at pretest, and this difference persisted at posttest. These results demonstrated that the dose of caffeine increased scores on state anxiety for individuals who consumed less than three caffeinated beverages weekly but had very little effect on performance of low intensity tasks, except for a hand-eye coordination test involving peripheral awareness. Perhaps longer continuous performance of more demanding tasks would be more sensitive.     

Impact of Experimentally Induced Positive and Anxious Mood on Alcohol Expectancy Strength in Internally Motivated Drinkers

The effects of musically‐induced positive and anxious mood on explicit alcohol‐related cognitions (alcohol expectancy strength) in 47 undergraduate students who consume alcohol either to enhance positive mood states (for enhancement motives) or to cope with anxiety (for anxiety‐related coping motives) were investigated. Pre‐ and post‐mood induction, participants completed the emotional reward and emotional relief subscales of the Alcohol Craving Questionnaire – Now. The hypothesis that anxiety‐related coping motivated drinkers in the anxious mood condition (but not those in the positive mood condition) would exhibit increases in strength of explicit emotional relief alcohol expectancies after the mood induction was supported. An additional, unanticipated finding was that enhancement‐motivated drinkers in the anxious condition also showed significant increases in strength of explicit emotional relief (but not emotional reward) alcohol expectancies. The hypothesis that enhancement‐motivated (but not anxiety‐related coping motivated) participants would exhibit increases in explicit emotional reward expectancies following exposure to the positive mood induction procedure was not supported. Taken together with past research findings, the current results highlight the importance of distinguishing between subtypes of negative affect (i.e., anxious and depressed affect) in exploring the affective antecedents of explicit alcohol outcome expectancies.     

Five-Factor Model and alcohol outcomes: Mediating and moderating role of alcohol expectancies

The aim of the present study was to examine the relationship between the Five-Factor Model of personality and alcohol expectancies (AEs) with different alcohol outcomes. The sample was composed of 738 participants (63.7% females). Path and regression analyses were performed to test the mediation and moderation effects. The results indicated that Neuroticism was related to alcohol consumption through Positive Alcohol Expectancies, and that Negative Alcohol Expectancies, but also Positive Alcohol Expectancies, partially mediated the relationship of Neuroticism to alcohol-related problems. In addition, Positive Alcohol Expectancies partially mediated the associations of extraversion and low conscientiousness with weekend Standard Drink Units (SDUs), and they completely mediated the associations of these personality variables with alcohol-related problems. Additional direct paths were found from low agreeableness to weekly SDUs and alcohol-related problems; and from low openness to weekend SDUs. Moderation effects of alcohol expectancies on personality and both alcohol use and alcohol-related problems were also found. The present research contributes new evidence on the influence of the five factors of personality on alcohol outcomes, and the mediation/moderation role of alcohol expectancies. These findings can be useful to develop prevention/intervention programmes.     

Caffeine, Cognition, and Persuasion: Evidence for Caffeine Increasing the Systematic Processing of Persuasive Messages

Caffeine is known to increase arousal, attention, and information processing–all factors implicated in facilitating persuasion. In a standard attitude-change paradigm, participants consumed an orange-juice drink that either contained caffeine (3.5 mg/kg body weight) or did not (placebo) prior to reading a counterattitudinal communication (anti-voluntary euthanasia). Participants then completed a thought-listing task and a number of attitude scales. The first experiment showed that those who consumed caffeine showed greater agreement with the communication (direct attitude: voluntary euthanasia) and on an issue related to, but not contained in, the communication (indirect attitude: abortion). The order in which direct and indirect attitudes were measured did not affect the results. A second experiment manipulated the quality of the arguments in the message (strong vs. weak) to determine whether systematic processing had occurred. There was evidence that systematic processing occurred in both drink conditions, but was greater for those who had consumed caffeine. In both experiments, the amount of message-congruent thinking mediated persuasion. These results show that caffeine can increase the extent to which people systematically process and arc influenced by a persuasive communication.     

Core beliefs,automatic thoughts and response expectancies in predicting public speaking anxiety

The present study examined the relationships between broad core cognitions, situation-specific automatic thoughts, and response expectancies in regard to their relative contributions to public speaking anxiety. Ninety-nine socially anxious participants (mean age = 20.25) completed measures of irrational beliefs and automatic thoughts specific to public speaking. Participants were then announced the task – giving a speech in front of a virtual reality audience – and response expectancies were measured. Subjective anxiety was measured just before the speech. As predicted, response expectancies and negative automatic thoughts specific to public speaking were each found to mediate the relationship between irrational beliefs and public speaking anxiety. Multiple mediation analysis indicated that the core irrational beliefs generated specific beliefs (i.e., response expectancies that primed automatic thoughts) that acted on speech-related anxiety.     

Understanding the Relationship Between Religiousness, Spirituality, and Underage Drinking: The Role of Positive Alcohol Expectancies

Research has consistently found that religiousness and spirituality are negatively associated with underage drinking. However, there is a paucity of research exploring the mechanisms by which these variables influence this important outcome. With 344 underage young adults (ages 18–20; 61 % women), we investigated positive alcohol expectancies as a mediator between religiousness and spirituality (measured separately) and underage alcohol use. Participants completed the Religious Commitment Inventory-10, Daily Spiritual Experiences Scale, Alcohol Expectancies Questionnaire, and Drinking Styles Questionnaire. Results indicate less positive alcohol expectancies partially mediate the relationship between both religiousness and spirituality and underage alcohol use. This suggests religiousness and spirituality’s protective influence on underage drinking is partly due to their influence on expectations about alcohol’s positive effects. Since underage drinking predicts problem drinking later in life and places one at risk for serious physical and mental health problems, it is important to identify specific points of intervention, including expectations about alcohol that rise from religious and spiritual factors.     

Predicting Adolescent Drinking From Alcohol Expectancy Values: A Comparison of Additive,Interactive, and Nonlinear Models1

Additive, interactive, and nonlinear models of alcohol expectancy values were compared using survey data from 1,758 high school students. Expectancies and values independently predicted drinking in the additive model. Expectancies were more important as predictors than were values, and negative expectancies were more important than positive expectancies. Significant expectancy-value interactions also were found. Drinking was highest when positive consequences were believed to be likely and desirable and was lowest when negative consequences were believed to be likely and undesirable. Significant nonlinearities indicated that beliefs about negative consequences had greater effects at lower levels of likelihood and evaluation whereas beliefs about positive consequences had greater effects at higher levels of likelihood and evaluation. However, the interactive and nonlinear effects were small.     

Impact of experimentally induced positive and anxious mood on alcohol expectancy strength in internally motivated drinkers

The effects of musically-induced positive and anxious mood on explicit alcohol-related cognitions (alcohol expectancy strength) in 47 undergraduate students who consume alcohol either to enhance positive mood states (for enhancement motives) or to cope with anxiety (for anxiety-related coping motives) were investigated. Pre- and post-mood induction, participants completed the emotional reward and emotional relief subscales of the Alcohol Craving Questionnaire - Now. The hypothesis that anxiety-related coping motivated drinkers in the anxious mood condition (but not those in the positive mood condition) would exhibit increases in strength of explicit emotional relief alcohol expectancies after the mood induction was supported. An additional, unanticipated finding was that enhancement-motivated drinkers in the anxious condition also showed significant increases in strength of explicit emotional relief (but not emotional reward) alcohol expectancies. The hypothesis that enhancement-motivated (but not anxiety-related coping motivated) participants would exhibit increases in explicit emotional reward expectancies following exposure to the positive mood induction procedure was not supported. Taken together with past research findings, the current results highlight the importance of distinguishing between subtypes of negative affect (i.e., anxious and depressed affect) in exploring the affective antecedents of explicit alcohol outcome expectancies.     

Effects of nicotine dose, instructional set, and outcome expectancies on the subjective effects of smoking in the presence of a stressor

The balanced placebo design (BPD) was used to evaluate the independent effects of nicotine dose and smoking-related expectancies on self-reported anxiety, urge to smoke, and withdrawal symptoms. After anxious mood was induced, participants smoked either a de-nicotinized cigarette or one with standard nicotine content. Nicotine dose was crossed with instructions that the cigarette was either de-nicotinized or standard. Nicotine cigarettes produced greater anxiety reduction than de-nicotinized cigarettes. Nicotine instructions attenuated anxiety only among those who held relevant expectancies. Nicotine dose and instructional set interacted such that either nicotine cigarettes or instructions that the cigarettes contained nicotine were sufficient to reduce urge to smoke. Implications of these findings and methodological issues regarding use of the BPD with cigarettes are discussed.     

Evaluations and expectancies of alcohol and marijuana problems among college students.

Two studies examined the associations between evaluations (good-bad) and expected likelihood (likely-unlikely) of alcohol- and marijuana-related problems and hazardous consumption and problems among college students. Participants provided data on alcohol use, alcohol-related problems, and expectancies and evaluations of alcohol problems; marijuana use indices, marijuana-related problems, marijuana effect expectancies, and likelihood and evaluations of marijuana problems. Evaluations of alcohol problems were positively related to the number of binge drinking occasions and alcohol-related problems. The interaction between evaluations and expectancies was significant in predicting the number of binge drinking occasions. Expectancies demonstrated a curvilinear relationship with binge drinking and alcohol-related problems. Marijuana users evaluated marijuana-related problems as less negative and less likely to occur than did nonusers. Expectancies, but not evaluations, of negative consequences were significantly associated with marijuana use intensity. Expectancies of problems demonstrated a curvilinear relationship with marijuana-use intensity and marijuana problems. Men evaluated alcohol and marijuana problems less negatively than did women. In summary, the expected likelihood of alcohol-marijuana problems and the evaluation of such problems represent a vulnerability factor associated with increased liability for hazardous alcohol and marijuana use.     

Social Anxiety and Specificity of Positive Alcohol Expectancies: Preliminary Findings

This preliminary study examined the relationship between social anxiety and specificity of positive alcohol outcome expectancies (AOE) in a community sample of 62 drinking adults. The sample was divided into subsets of socially anxious (n = 17) and nonsocially anxious (n = 45) men and women. The Drinking Expectancy Questionnaire (DEQ) and Alcohol Expectancies in Social Evaluative Situations Scale (AESES) were used to determine if groups differed in the general positive AOE they hold, or only in AOE specific to social situations. ANOVAs revealed that socially anxious individuals had greater positive AOE specific to social situations (DEQ—Assertion scale and AESES) than nonsocially anxious individuals, with no differences in other positive AOE. Partial correlations controlling for social anxiety revealed that AOE specific to social situations correlated with greater drinking and alcohol dependency levels. Findings indicate that identification of AOE specific to social situations may be useful in classifying socially anxious individuals at risk for alcoholism and as a focus of expectancy challenge strategies for individuals with co-occurring social anxiety and drinking problems.     

Ecstasy Use,Outcome Expectancies,and Sexual Risk Taking

Ecstasy has become one of the most widely used illicit drugs in Australia. This study investigated outcome expectancies as possible motivating and maintaining factors in ecstasy use and sexual risk‐taking behaviour. A sample of regular ecstasy users (N = 220) from Sydney and Canberra, Australia, was recruited for structured face‐to‐face interviews. They also completed an Ecstasy Expectancy Questionnaire. Seven of eight subscales significantly differentiated regular users from non‐users. Interestingly, light and heavier users held similar outcome expectancies, except that light users endorsed items on the sexual enhancement subscale more strongly than heavier users. Further investigation showed that the level of sexual risk taking observed in this sample was high, with the majority of participants reporting multiple partners, “casual” sexual encounters, sex under the influence of substances, and inconsistent condom use. Using logistic regression analyses, a key finding was that positive sex‐related ecstasy outcome expectancies were associated with involvement in disinhibited sexual behaviour under the influence of ecstasy. These effects persisted after statistically controlling for the frequency of ecstasy use. The findings suggest that sexual risk taking is related not only to the disinhibiting properties of ecstasy but also to beliefs that users hold about the effects of the drug.     

Three consecutive nights of sleep loss: Effects of morning caffeine consumption on subjective sleepiness/alertness,reaction time and simulated driving performance

Caffeinated products are often consumed as a popular countermeasure to the effects of sleep loss. However, the efficacy of caffeine to exert these effects after consecutive nights of sleep loss is poorly understood. The aim of this study was to investigate the effects of three consecutive nights of restricted sleep and morning caffeine consumption on subjective ratings of sleepiness/alertness, reaction time, and simulated driving performance. Twenty healthy, habitual caffeine consumers (11 females; age: 23.3 ± 5.7 y; BMI: 22.3 ± 3.5 kg⋅m⁻²; caffeine intake: 204 ± 89 mg⋅day⁻¹; Mean ± SD) who had normal sleeping patterns (≥8 h⋅night⁻¹) participated in this double-blind, placebo-controlled, randomised study. Following one night of normal sleep (≥8 h time in bed (TIB)), participants underwent three consecutive nights of restricted sleep (5 h TIB). Participants received caffeine (200 mg; n = 10) or placebo (n = 10) capsules each morning and all participants received caffeine (100 mg) capsules each afternoon. Subjective ratings of alertness, concentration and tiredness were measured before and 1 h after morning capsule administration. Choice Reaction Time (CRT) was examined 1 h after morning capsule administration, with response speed and accuracy as outcome variables. Driving performance was assessed using a 30 min simulated driving task, with lateral (standard deviation of lane position [SDLP]; total number of line crossings [LC]) and longitudinal (standard deviation of speed [SDSP]) measures of vehicle control as outcome variables. Alertness and concentration significantly decreased, and tiredness increased across the three days of sleep loss. Caffeine only marginally alleviated these effects. No differences were observed between treatments or across trial days for response speed and accuracy on the CRT task. Likewise, no significant differences were observed between groups or across trial days for any measures of simulated driving performance. Overall, results from this study indicate that three consecutive days of sleep loss influence subjective ratings of alertness, concentration and tiredness, but does not alter CRT or simulated driving performance. Caffeine may alleviate some of the negative subjective effects imposed by restricted sleep, but the efficacy of caffeine to attenuate performance changes in CRT and driving performance were unable to be observed.     

Cardiovascular reactivity, mood, and task performance in deprived and nondeprived coffee drinkers

Forty habitual, heavy coffee drinkers (M = 5.7 cups/day) participated in two experimental sessions. Participants were deprived of their morning coffee for one of the laboratory sessions, not deprived the other. During each session, subjects consumed 12 oz of caffeinated coffee, decaffeinated coffee, or caffeine-free herbal tea. Measurements of heart rate, blood pressure, mood, and catecholamine response to deprivation and consumption of the beverage, alone and in combination with challenging tasks, were made. This study found that caffeine continues to cause blood pressure increases with chronic, heavy consumption and that these effects do not appear to habituate with regular use. Subjects reacted to behavioral challenge with fewer negative mood effects if they had consumed caffeine or coffee. Mild caffeine deprivation was associated with symptoms of stress.     

Effects of d-amphetamine and caffeine on schedule-controlled and schedule-induced responding.

The effects of d-amphetamine and caffeine were studied on rates and patterns of lever pressing and schedule-induced licking under fixed-interval schedules of food pellet presentation. In addition, the effects of caffeine were studied on lever pressing and licking under a multiple fixed-ratio fixed-interval schedule. Caffeine reduced mean overall rates of licking at lower doses than it reduced mean overall rates of pressing under the fixed-interval schedules, but the effects of caffeine on both licking and lever pressing depended largely on the control rate of responding. d-Amphetamine reduced mean overall rates of lever pressing and licking at about the same dose, but the effects of d-amphetamine also were a function of the control rate of responding.     

Expect the unexpected: ability, attitude, and responsiveness to hypnosis

Participants' expectancies and hypnotic performance throughout the course of a standardized, individually administered hypnotic protocol were analyzed with a structural equation model that integrated underlying ability, expectancy, and hypnotic response. The model examined expectancies and ability as simultaneous predictors of hypnotic responses as well as hypnotic responses as an influence on subsequent expectancies. Results of the proposed model, which fit very well, supported each of the 4 major hypothesized effects: Expectancies showed significant stability across the course of the hypnosis protocol; expectancies influenced subsequent hypnotic responses, controlling for latent ability; hypnotic responses, in turn, affected subsequent expectancies; and a latent trait underlay hypnotic responses, controlling for expectancies. Although expectancies had a significant effect on hypnotic responsiveness, there was an abundance of variance in hypnotic performance unexplained by the direct or indirect influence of expectation and compatible with the presence of an underlying cognitive ability.