"There are no controlled studies that show any productivity benefit to a normal person taking Adderall."
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"A 2015 meta-analysis of high quality clinical trials confirmed that therapeutic doses of amphetamine and methylphenidate result in modest improvements in performance on working memory, episodic memory, and inhibitory control tests in normal healthy adults. Therapeutic doses of amphetamine also enhance cortical network efficiency, an effect which mediates improvements in working memory in all individuals. Amphetamine and other ADHD stimulants also improve task saliency (motivation to perform a task) and increase arousal (wakefulness), in turn promoting goal-directed behavior. Stimulants such as amphetamine can improve performance on difficult and boring tasks and are used by some students as a study and test-taking aid." 
Sources 21,32,33,34, 35 are:
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Ilieva IP, Hook CJ, Farah MJ (January 2015). "Prescription Stimulants' Effects on Healthy Inhibitory Control, Working Memory, and Episodic Memory: A Meta-analysis". J. Cogn. Neurosci.: 1â"21. doi:10.1162/jocn_a_00776. PMID 25591060.
Devous MD, Trivedi MH, Rush AJ (April 2001). "Regional cerebral blood flow response to oral amphetamine challenge in healthy volunteers". J. Nucl. Med. 42 (4): 535â"542. PMID 11337538.
Wood S, Sage JR, Shuman T, Anagnostaras SG (January 2014). "Psychostimulants and cognition: a continuum of behavioral and cognitive activation". Pharmacol. Rev. 66 (1): 193â"221. doi:10.1124/pr.112.007054. PMID 24344115.
Malenka RC, Nestler EJ, Hyman SE (2009). "Chapter 10: Neural and Neuroendocrine Control of the Internal Milieu". In Sydor A, Brown RY. Molecular Neuropharmacology: A Foundation for Clinical Neuroscience (2nd ed.). New York, USA: McGraw-Hill Medical. p. 266. ISBN 9780071481274. "Dopamine acts in the nucleus accumbens to attach motivational significance to stimuli associated with reward."