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PsychopharmacologyDOI 10.1007/s00213-008-1369-3 When we enhance cognition with Adderall, do we sacrificecreativity? A preliminary study Martha J. Farah & Caroline Haimm &Geena Sankoorikal & Anjan Chatterjee Received: 19 June 2008 / Accepted: 3 October 2008 in the lower range of the normal distribution experience Rationale Adderall (mixed amphetamine salts) is used by healthy normal individuals to enhance attention. Researchwith healthy normal participants and those with attention Keywords Cognition . Creativity . Adderall .
deficit hyperactivity disorder indicate a possible inverse relationship between attentional function and creativity. Thisraises the possibility that Adderall could decrease creativityin people using it for cognitive enhancement.
The past decade has seen a rise in the use of prescription Objective This study was designed to find out whether stimulants by normal healthy individuals for cognitive Adderall impairs creativity in healthy young adults.
enhancement. McCabe et al. estimated that 4% of Material and methods In a double-blind placebo-controlled American college students had used a stimulant for study, the effects of Adderall on the performance of 16 healthy nonmedical purposes in the past year and found that on young adults were measured on four tests of creativity from some campuses, the past year prevalence was a high as the psychological literature: two tasks requiring divergent 25%. Hundreds of adult respondents to a Nature Magazine thought and two requiring convergent thought.
poll on cognitive enhancement reported using prescription Results Adderall affected performance on the convergent stimulant medication for this purpose (Maher tasks only, in one case enhancing it, particularly for lower- The most commonly used stimulants for cognitive performing individuals, and in the other case enhancing it for enhancement are Adderall (mixed amphetamine salts) and the lower-performing and impairing it for higher-performing Ritalin (methylphenidate), both of which are typically prescribed for the treatment of attention deficit hyperactiv- Conclusion The preliminary evidence is inconsistent with ity disorder. Their ability to enhance the cognition of the hypothesis that Adderall has an overall negative effect normal healthy people has been demonstrated by a number on creativity. Its effects on divergent creative thought cannot of laboratory studies with tests of problem solving and be inferred with confidence from this study because of the executive function (e.g., Elliott et al. ambiguity of null results. Its effects on convergent creative The use of stimulant medication for cognitive enhance- thought appear to be dependent on the baseline creativity of ment by healthy individuals raises a number of ethical the individual. Those in the higher range of the normal issues, which have become a focus of discussion and distribution may be unaffected or impaired, whereas those analysis in the neuroethics literature (e.g., Farah et al. ;Hyman Sahakian and Morein-Zamir Theseissues include safety, especially how a medication’s risk-benefit ratio is changed when the benefit is enhancement M. J. Farah (*) : C. Haimm : G. Sankoorikal : A. Chatterjee rather than therapy. They also include the individual’s Center for Cognitive Neuroscience, University of Pennsylvania, freedom to enhance or not to enhance. The latter may be difficult to maintain when and if cognitive enhancement Philadelphia, PA 19104, USAe-mail: mfarah@psych.upenn.edu becomes so widespread that it is preferred or even expected by schools and employers. Fairness is another issue raised ADHD on tests of creativity, although only with repeated any cognitive enhancement, as its advantages will undoubt- testing, relative to the untreated children who apparently lost edly be enjoyed disproportionately by the wealthy and well interest in the task. Funk et al. found no effect.
connected. Indeed, unequal access to cognitive enhance- Douglas et al. (found that high doses of methylphe- ments may, over time, have a deleterious effect on society nidate improved the performance of ADHD subjects on a as a whole by further reducing mobility between socioeco- test of creativity. Finally, Smartwood et al.( ) found that nomic classes and increasing stratification.
methyphenidate impaired creativity in children with ADHD An issue that has yet to be addressed in the neuroethics by one of their measures. In sum, there is no clear pattern in literature is the effect of cognitive enhancement on what the literature on ADHD and stimulants regarding stimulant could be called “cognitive style”. Do the prescription stimulants currently being used for enhancement influence The goal of our study was to examine the effects of a the way people think? More specifically, do they enhance widely used stimulant, Adderall (mixed amphetamine certain forms of thought at the expense of creativity? The salts), on creativity in healthy young adults. In overview, impact of cognitive enhancement on the individual and on we conducted a double-blind placebo-controlled study of society more generally depends on the answer to this the effects of Adderall on the performance of healthy young question. The societal effects could be particularly conse- adults on four tests of creativity from the psychological quential. If cognitive enhancement continues to be more literature. These tests were given as part of a larger battery widely practiced and does decrease creativity, the effect on of cognitive tests. In order to capture as broad a sample of society as a whole could be grave. It would mean less creative thinking as possible, we administered two tasks creativity in our workforce and in our leaders.
requiring divergent thought and two requiring convergent Psychologists define creativity as the process of access- thought, and within each of these pairs, one emphasizing ing seemingly irrelevant or unrelated information in ways verbal processes and responses and one emphasizing that serve a purpose or solve a problem (Runco This suggests that a certain degree of distractability may be arequirement for creative thought, and the reports of somecreative individuals are consistent with this. The mathema- tician Poincare, who is often quoted for his observations onmathematical creativity, emphasized the value of not Participants Sixteen healthy adult subjects (four men, 12 focusing one’s mind but letting it range widely. He described women) between the ages of 21 and 30 (mean=21.25, SD= creativity as the discovery of “unsuspected kinship… 0.45) participated. Exclusion criteria included the follow- between facts long known but wrongly believed to be ing: history of neurological or psychiatric illness, history of strangers to one another”, and he recounted his failure to epilepsy or seizure disorder, history of glaucoma, history of solve a problem when he focused on it, only to have the gastrointestinal blockage, history of heart disease, history solution come to mind later (Ackerman Charles of thyroid problems, or history of a diagnosed learning Darwin attributed his insights in part to his tendency to disability. Subjects were excluded if they were regular users of notice irrelevant stimuli, which he was so unable to screen nicotine, cocaine, opiates, narcotic pain killers, tranquilizers, out that he required absolute silence to work (Kasof ).
methamphetamine, or ecstasy (MDMA). Subjects who con- Research with ordinary people lends further support to the sumed more than 700 mg of caffeine per day were excluded association of creativity with distractability (e.g., Ansburg from participation in the study. Furthermore, subjects who and Hill Dykes and McGhie ; Finke et al. used warfarin, phenytoin, phenobarbitol, primidone, nortipty- line, amytryptyline, doxepin, desipramine, clomipramine, ). For example, normal adults who scored highly on a imipramine, fluoxetine, fluvoxamine, paroxetine, sertaline, battery of creativity tests showed more intrusion errors in a clonidine, guanethidine, D-amphetamine, methylphenidate, dichotic listening task (Dykes and McGhie ). Similar- and Wellbutrinin in the past 14 days were not allowed to ly, individuals with attention deficit hyperactivity disorder participate. We excluded women who were pregnant or (ADHD) are often described as unfocused but creative likely to become pregnant and subjects who regularly used (Palladino ), and a recent study of highly creative over-the-counter antihistamines like Claritin D-24 or children found that 40% met criteria for ADHD (Healy and Benadryl. Eligibility was determined based on a phone screening session. The small size of our sample precludes the There is a small literature on stimulant effects on creativity investigation of gender effects in this study.
in ADHD, but the outcomes of the different studies aredifficult to reconcile. Solanto and Wender () found that Procedure The data reported here were collected in two methylphenidate enhanced the performance of children with sessions of about 2.5 h, approximately 1 week apart, scheduled to begin at the same time of day and beginning Alternative Uses Task This is a standard measure of no later than 3:30 PM so that participants would be finished divergent thinking, whose stimuli and responses are verbal.
by no later than 6 PM. A separate 1-h session was scheduled Following Guilford ), participants are given the name on a different day prior to these sessions for the purpose of of an object and asked to come up with as many alternative familiarizing participants with the tasks. Familiarization uses as they can for the object within a specified time involved receiving the instructions and performing practice period; for this study, the period was 80 s. Participants were trials. Participants were instructed to avoid eating a heavy instructing with the help of an example: If given “tissue” as meal in the 3 h prior to testing. Visually indistinguishable the object, an example of an appropriate alternative use pills containing 10 mg mixed amphetamine salts or inert would be a “blanket for a doll”. They were told that the ingredients were administered to the participants 30 min alternative use must make sense, so a response such as “eat before the beginning of testing by a research assistant as food” would not count. Three objects were named per who was blind to pill identity. Half of the subjects session: shoe, button, and key in one session and brick, received placebo first and half received amphetamine paperclip, and newspaper in the other. Session was counter- first. Two versions of each task, with different items, were balanced with drug condition. The responses of the used on the first and second day of testing, resulting in participants were recorded and scored by three independent each task version being performed equally often by judges, blind to condition, for originality, fluency, flexibil- participants on amphetamine and placebo. Four tasks to ity, and detail of the response according to the criteria of assess creativity were administered in the same order for each subject: the Alternative Uses Task, the RemoteAssociation Task, Group Embedded Figures Task, and Drawing task from the Abbreviated Torrance Test for the drawing task from the Abbreviated Torrance Test for Adults The Abbreviated Torrance Test for Adults is a Adults. The testing session also included other tasks standardized, abbreviated form of the Torrance Test of unrelated to creativity, which are not described further Creative Thinking (Goff used to assess divergent here, and task order was rotated over participants. Two thinking. It includes two picture-drawing tasks and a single of the tasks (Remote Association and Alternative Uses) verbal task. In order to make within-subject comparisons, were performed at varying points in the session, only the picture items were used, one in each testing between a 0.5 and 3 h after pill administration, with session. Participants were given one of the pictures in Fig. order matched between the placebo and drug sessions (counterbalanced with drug condition) and told “Use the for a given participant. The other two tasks (Embedded incomplete figure below to make a picture. Try to make Figures and Torrence) were performed at the end of the your picture unusual. Your picture should communicate as session by all participants, which is about 3 h after pill interesting and as complete a story as possible. Be sure to give your picture a title.” They were given 90 s to carry thisout. Scoring was done by three independent judges, blind to Remote Association Task This provides a measure of condition, according to the criteria of Torrance, with the convergent creative thinking and insightful problem solving exception that scores for the verbal section and for the in the verbal domain (Mednick ). Participants were relations between the two figures were omitted. Thus, presented with three words at a time and asked to supplythe one word that was associated with the other three words.
Subjects had 1 min to complete each triad. Fifteen triads were presented in each session, counterbalanced with drugcondition. An example of a triad is “manners”, “round”, and Group Embedded Figures Task This nonverbal taskrequires participants to regroup the elements of a geometricdesign in ways that reveal the figures embedded in it andhas been used as a test of convergent creative thinking(Noppe Witkin et al. ). An example is shown inFig. . The original test of 18 items was divided into twosets of nine administered in sessions 1 and 2, and in thepresent study, participants outlined as many embeddedfigures as they could from one section in 3.5 m; set wascounterbalanced with drug condition.
performance was scored according to norm-referenced Adderall and placebo sessions, and involved three different measures (fluency, originality, elaboration, and flexibility) participants (i.e., one participant was an outlier in two and criterion-referenced creativity indicators (openness, unusual visualization, movement, and/or sound, richness,and/or colorfulness of imagery, abstractness of title, context, Comparison of performance on Adderall and placebo synthesis of two or more figures, internal visual perspective, Matched pairs t tests were carried out to assess the effects expressions of feelings and emotions, and fantasy; Goff of Adderall on performance in the four creativity tasks. The hypotheses under consideration include facilitation of In contrast to the convergent thinking tasks, which have performance by Adderall, impairment of performance by objectively right and wrong answers, participants’ Adderall, and no effect of Adderall. Because we do not have responses to the two divergent thinking tasks must be a directional prediction, reported p values are two-tailed.
evaluated by blind raters. Three undergraduate students, We begin with the convergent thinking tasks. In the blind to condition, rated participants’ productions in the Remote Association Test, participants obtained on average Alternate Uses task and the drawing task from the 5.07 out of 15 correct in the placebo condition and 5.00 in Abbreviated Torrance Test according to the criteria described the Adderall condition, t(14)=0.120, ns. In the Group above. Their ratings have an intraclass correlation of 0.817 Embedded Figures Task, participants identified 6.07 of nine overall and were averaged for purposes of the analyses shapes in the placebo condition and 7.13 in the Adderall condition, t(14) =−2.477, p=0.027. Turning to the divergentthinking tasks, in the Alternative Uses Task, participants’responses were scored 33.92 on average scored in the placebo condition and 33.45 in the Adderall condition, t(14)=0.300, ns. Finally, in the drawing task of the Abbreviated In overview, our data analysis consisted of outlier removal Torrance Test for Adults, participants’ responses were rated followed by matched pairs t tests and analyses of variance 12.51 on average in the placebo condition and 13.44 in the for the effect of Adderall on creativity in each of the four Adderall condition, t(14)=−1.019, ns.
tasks and regression analyses to assess the effect of In sum, Adderall reliably affected performance on the Adderall as a function of individual differences in creativity Embedded Figures Task. On this measure, Adderall enhanced creativity; participants were reliably more ableto discover embedded shapes that require distancing oneself Outlier removal For each task, any participant whose from the most natural parse of a large pattern and performance fell more than 2.5 SD from the mean in the recombining the elements of that pattern in a less obvious placebo or drug condition was eliminated from the way. For the other three tests, average performance was analyses. Because the comparisons were within-subject, similar between the placebo and Adderall conditions. The elimination of a participant’s data from one session of a null results with these three tasks could indicate a true lack task, placebo, or drug resulted in the elimination of both of effect of the drug on the creative thought processes tapped sessions’ data for that task from the analysis. There were by these tasks or a lack of power in our experimental design.
just four outliers identified among the 128 subject-by-task- Power analysis suggests that with the sample size we used by-drug data points using these criteria; in other words, and power of 0.80, we would be able to detect only a about 3% of the data were classified as outliers by our relatively substantial effect of size 0.75, which is medium– method. These occurred once for each task, equally often in large by Cohen’s classification of effect sizes. The lack ofdrug effect on creativity in these three tasks should thereforebe interpreted with caution. In contrast, the finding ofstatistically significant enhancement of creativity in one taskcan be interpreted with confidence as contradicting thehypothesis that Adderall diminishes creativity.
To examine the effects of drug along with those of session order, we carried out analyses of variance with drug(Adderall or placebo) as a within-subjects factor and order(Adderall first or placebo first) as a between-subjects factor.
Recall that order was confounded with the specific itemspresented in each task: The first session test items were thesame for all participants, regardless of whether they had Fig. 2 Figures to be completed in the Abbreviated Torrance Test forAdults taken Adderall or placebo, and the same was true for the second session test items. Also relevant to the interpretation individuals, the prediction tested by the regression is that of order effects, on a different day prior to the first session, lower placebo performance will be associated with larger participants received task instructions and performed drug effects, and the p values are accordingly one-tailed.
practice trials. Finally, order was a between-subjects factor, Placebo performance predicted the size of the drug effect so incidental differences in the two groups of participants in both of the convergent thinking tests, p<0.001 for the could manifest themselves as an “order” effect in this study.
Remote Associates Test and p=0.003 for the Embedded As with the t test, the ANOVA showed that the effect of Figures Test. In each case, the direction of the relationship drug was significant for only one task, Embedded Figures, was as predicted: larger enhancement effects for lower- F(1, 13)=5.83, p=0.031, all other tasks ns. There were no performing individuals. The two divergent thinking tests main effects of order and no interactions between drug and did not show this pattern. For the Alternative Uses Task, the order with the exception of an interaction for the Remote drug effect was not significantly predicted by placebo Associates Test, F(1, 13)=23.22, p<0.001. Examination of performance, p=0.142, and the drawing task showed a the means indicates that the drug enhanced performance for borderline trend, p=0.082, but in the other direction (more those who took it second (from 4.00 to 5.70 correct on enhancement for better performing participants). Consistent average), whereas it impaired performance for those who with the results of the earlier ANOVA, the Remote took it first (from 6.00 to 4.38 on average).
Associates Test also showed a significant order effect, withlarger drug effects for participants who received Adderall in Individual differences in drug effect Given the finding that Adderall enhanced performance in one creativity task, the A problem with these analyses is that the dependence of next set of statistical analyses tested the possibility that drug effect on placebo performance could reflect regression Adderall may affect performance differently in different toward the mean. That is, to the extent that there is subjects, depending on their baseline or placebo level of measurement error in the data, participants who scored well performance. The dependence of a drug effect on partici- in the placebo condition would be expected to score less pant level of ability can entirely mask the effect of the drug well on average in a different session, and participants who when the whole sample of participants is considered scored poorly in the placebo condition would be expected together. This was first observed by Kimberg et al. ( to score somewhat better on average in a different session.
with the dopamine agonist bromocriptine. Their sample’s The ideal way to assess the effect of a participant’s baseline mean performance on an executive function battery was ability on the drug effect would be to have a second numerically almost identical on drug and placebo, similar to measure of placebo performance so that the measure used the findings with three of the tasks in this study. However, as the predictor variable is not the one used to calculate the after a median split on working memory span, it was found drug effect. Unfortunately, we did not collect second that the lower half of the participants improved significantly placebo measures with our participants. A second-best on the drug and the upper half declined by the same solution is to replace placebo performance as a predictor amount. A similar, though less extreme, pattern has been variable with the average of placebo and Adderall perfor- found in studies of the effects of methylphenidate and mance. To the extent that the drug effect is indeed larger for amphetamine on executive functions, including working participants with lower placebo performance, the use of a memory (Mattay et al. , Mehta et al. ) and placebo–Adderall average will bias the results against inhibitory control (DeWit et al. ). In these studies, finding the hypothesized effect. However, at least this participants who performed worst on placebo tended to method of testing is at least not biased in favor of finding improve the most with stimulant medication, whereas those who performed best tended to show less improvement or We reanalyzed the data from the two convergent even show worse performance with the stimulant.
thinking tests using the average of placebo and Adderall To determine whether Adderall has an enhancing effect performance as the estimate of participants’ baseline level on creativity for the less creative participants that declines of creativity, along with session order as before. Despite the or even reverses for the more creative participants, we bias in this analysis against finding an effect of baseline on performed a regression analysis. The dependent measure drug effect, the relationship remained significant for the was drug effect, that is, the difference in performance Remote Associates Test, p = 0.027. For the Embedded between placebo and Adderall. The independent or predic- Figures Test, which showed an overall significant enhance- tor variables were the participants’ performance on placebo ment with Adderall, the trend for greater enhancement for and the order in which they performed two conditions lower-performing subjects was borderline significant, p= (placebo first or Adderall first). The former is a measure of 0.086. Figure shows the performance of participants the participant’s baseline ability level. Given the findings whose average placebo–Adderall performance level fell just cited of greater enhancement for lower-performing above the median (left) and below the median (right) in the mance was below or above themedian (of the mean of placeboand Adderall conditions) onplacebo (black) and on Adderall (white) in the a Remote Asso-ciates Test and the b EmbeddedFigures Test. Conventional errorbars are not shown because placebo–Adderall comparisonsare within-subject Mean Performance
Mean Performance
placebo and Adderall conditions of the Remote Associates effects of Adderall on convergent and divergent thought, it may also reflect differences in the sensitivity of the tasks.
By their nature, convergent thinking tasks have objectiveright answers, whereas the success of divergent thinking is a more subjective matter and must be measured by theratings of others. Although our inter-rater reliability was Does cognitive enhancement with Adderall impair creativity? good, it was not perfect, and this would make the divergent In this preliminary exploration of the issue, using four tasks weaker instruments for measuring drug effects on different tests of creative ability in healthy young adults, we creativity than the convergent tasks.
found no evidence of a general impairment. On the contrary, Other aspects of the design that would be expected to Adderall enhanced performance on one test of convergent influence the sensitivity of the experiment include sample creative thought. For this test, the Embedded Figures Test, size, test length, dosage, and dose timing. Although a sample there was also a trend toward disproportionate enhancement of 16 participants is comparable in size to some samples used of the lower-performing participants. For another test of to demonstrate effects of stimulant medications on healthy convergent creative thought, the Remote Associates Test, participants (e.g., Mehta et al. there is no doubt that a Adderall also affected performance, although the direction of larger sample would confer more power on the study. Tests the effect depended on the creativity of the participant; the with more items for each task would also have a beneficial drug enhanced creativity for the lower-performing participants effect on the sensitivity of the research. Although the dose and impaired it for the higher-performing participants. This we used, 10 mg, is a commonly used dose for therapeutic pattern has been noted in other studies of stimulants and and research purposes (e.g., de Wit et al. many cognition and is not unique to creative thought (DeWit et al.
studies have used higher doses, and a higher dose in the present study might have led to different results. Finally, These results are reassuring in view of the increasing although two of the tasks were administered approximately number of healthy people using stimulant medications to 3 h after pill administration when plasma levels of the drug enhance cognition. They suggest that healthy individuals would be high (the Torrance test and the Embedded Figures seeking to enhance their cognitive abilities with Adderall test), the timing of two others varied over participants, are not necessarily impairing their creativity. However, just with some performing them as early as 0.5 h after pill as stimulants may impede high ability individuals in other administration when the drug effects would have been just cognitive tasks, Adderall may impair rather than enhance onsetting (the Alternative Uses Task and the Remote the creativity of highly creative individuals, judging from Association task). Taken together, these considerations the results of the Remote Association Task.
suggest that the effects of Adderall on creativity may well The present study assessed creativity using four different have been underestimated by the present study. Never- tasks, including verbal and nonverbal tests of convergent theless, the findings of reliable enhancement effects of and divergent creative thought. Adderall was found to Adderall in one task and ability-dependent effects in affect performance on the convergent tasks only. Although another task tell us that the answer to the title question is this may reflect a fundamental difference between the not a simple “yes”. The neuroethical worry that widespread stimulant use could create a general downward shift in the Kasof J (1997) Creativity and breadth of attention. Creat Res J creativity of the population is assuaged by the present Kimberg DY, D’Esposito M, Farah MJ (1997) Effects of bromocrip- tine on human subjects depend on working memory capacity.
NeuroReport 8:3581–3585 Maher B (2008) Poll results: look who’s doping. Nature 452:674–675 N000140710034 and NIH grants R01-HD043078 and R01-HD055689.
Martindale B (1995) Childhood antecedents of schizophrenia. Envi- The authors thank Geoff Aguirre for serving as medical monitor for this ronmental influences should not be ignored. BMJ 310:57 study and Trevor Robbins and two anonymous reviewers for helpful Mattay VS, Callicott JH, Bertolino A, Heaton I, Frank JA, Coppola R, comments on an earlier draft of this article.
Berman KF, Goldberg TE, Weinberger DR (2000) Effects ofdextroamphetamine on cognitive performance and corticalactivation. NeuroImage 12:268–275 Mattay VS, Goldberg TE, Fera F, Hariri AR, Tessitore A, Egan MF, Kolachana B, Callicott JH, Weinberger DR (2003)Catechol O-methyltransferase val158-met genotype and indi- Ackerman D (2004) An alchemy of mind. Simon & Schuster, New vidual variation in the brain response to amphetamine. PNAS Ansburg PI, Hill K (2003) Creative and analytic thinkers differ in their McCabe SE, Knight JR, Teter CJ, Wechsler H (2005) Non-medical use of attentional resources. Pers Individ Differ 34:1141–1152 use of prescription stimulants among US college students: de Wit H, Enggasser J, Richards J (2002) Acute administration of prevalence and correlates from a national survey. Addiction d-amphetamine decreases impulsivity in healthy volunteers.
Mednick SA (1962) The associative basis of the creative process.
Douglas VI, Barr RG, Desilets J, Sherman E (1995) Do high doses of stimulants impair flexible thinking in attention-deficit hyperactivity Mehta M, Owen A, Sahakian B, Mavaddat N, Pickard J, Robbins T disorder? J Am Acad Child Adolesc Psychiatry 34:877–885 (2000) Methylphenidate enhances working memory by modulat- Dykes M, McGhie A (1976) A comparative study of attentional ing discrete frontal and parietal lobe regions in the human brain.
strategies of schizophrenic and highly creative normal subjects.
Noppe LD (1996) Progression in the service of the ego, cognitive Elliott R, Sahakian BJ, Matthews K, Bannerjea A, Rimmer J, Robbins styles, and creative thinking. Creativity Research Journal 9:28– TW (1997) Effects of methylphenidate on spatial working memory and planning in healthy young adults. Psychopharma- Palladino LJ (1999) Dreamers, discoverers and dynamos. Random Farah MJ, Illes J, Cook-Deegan R, Gardner H, Kandel E, King P, Rawlings S (1985) Behaviour and skills of severely retarded adults in Parens E, Sahakian B, Wolpe PR (2004) Neurocognitive hospitals and small residential homes. Br J Psychiatry 146:358– enhancement: what can we do and what should we do. Nat Rev Runco MA (2004) Creativity. Annu Rev Psychol 55:657–687 Finke RA, Ward TB, Smith SM (1992) Creative cognition: theory, Sahakian B, Morein-Zamir S (2007) Professor’s little helper. Nature research and applications. The MIT Press, Cambridge, MA Funk JB, Chessare JB, Weaver MT, Exley AR (1993) Attention deficit Solanto MV, Wender EH (1989) Does methylphenidate constrict hyperactivity disorder, creativity, and the effects of methylpheni- cognitive functioning. J Am Acad Child Adolesc Psychiatry Goff T (2002) Abbreviated Torrance Test for Adults Manual.
Swartwood MO, Swartwood JN, Farrell J (2003) Stimulant treatment Scholastic Testing Service, Bensenville, IL of ADHD: effects on creativity and flexibility in problem Guilford JP (1957) Creative abilities in the arts. Psychol Rev 64:110– Wallach M (1970) Creativity. In: Mussen P (ed) Carmichael’s Healey D, Rucklidge JJ (2006) An investigation into the relationship handbook of child psychology. Wiley, New York, pp 1211– among ADHD symptomatology, creativity, and neuropsycholog- ical functioning in children. Child Neuropsychol 12:421–438 Witkin HA, Oltman PK, Raskin E, Karp SA (2002) Group embedded Hyman S (2006) Improving our brains. BioSocieties 1:103–111 figures test manual. Mind Garden, Redwood City, CA

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