Wait really? That can't be true. Are you saying the experience of thousands of students and journalists who use contraband stimulants to make their deadlines is illusory?
Can you please post the full citations for the studies above?
1) Really. There is a big literature base on this that you might be better equipped to summarize. Conceptually, you can categorize the literature base into Cognition and Performance.
a. Cognition: Do stimulants improve cognition? Broad strokes, no. In non-ADHD samples, stimulants offer limited to no effect on cognitive tasks. There is some evidence of a small effect on rote memorization that does not seem to increase actual performance (i.e., they can sit and memorize better, but when they are later queried, there is no difference). Of course, this gets more complicated based upon type of task and which stimulant on what dosage.
b. Performance-Outcome: Does taking stimulants actually improve outcomes? Non-ADHD stimulant use doesn't increase GPA, nor offer protection against decline in grades. There's a lot of this stuff. I'm interested in it from the ethics standpoint on cognitive enhancement and how it ties into the literature about testosterone's effects on risk in stock trading.
2) Some starting points. It's interesting to see if one's perception of performance has anything to do with one's actual performance. Bonus article about expectation effects.
Ilieva, I., et al. (2013). "Objective and subjective cognitive enhancing effects of mixed amphetamine salts in healthy people." Neuropharmacology 64: 496-505.
Arria, A. M., et al. (2017). "Do college students improve their grades by using prescription stimulants nonmedically?" Addict Behav 65: 245-249.
Pelham, W. E., et al. (2022). "The effect of stimulant medication on the learning of academic curricula in children with ADHD: A randomized crossover study." J Consult Clin Psychol 90(5): 367-380.
Cropsey, K. L., et al. (2017). "Mixed-amphetamine salts expectancies among college students: Is stimulant induced cognitive enhancement a placebo effect?" Drug and alcohol dependence 178: 302-309.
Looby, A., et al. (2022). "Expectation for stimulant type modifies caffeine’s effects on mood and cognition among college students." Experimental and Clinical Psychopharmacology 30: 525-535.