The Mind Adds Weight: Scientific Evidence from the Gym and Beyond
The Dantzig Effect in the Gym and in the Mind
In a previous post, I wrote about my experience with the bench press. What struck me
was how often the real failure happened before the bar even moved. Lifters (myself included) would stare at the plates, convince themselves it was too heavy, and give up before giving the attempt a fair shot. The mind had already added weight to the bar.
Some readers liked the idea, others were skeptical. Isn’t this just a motivational story? Where’s the evidence?
That got me thinking about the broader principle. There’s a famous story about mathematician George Dantzig: arriving late to class, he saw two problems on the board and copied them down as homework. He worked on them for a few days, handed them in, and left his professor stunned - because the “homework” turned out to be unsolved problems in statistics. Dantzig had cracked them simply because he didn’t know they were supposed to be impossible.
That’s the same effect I saw under the bar: when you strip away the story of impossibility, the “mental weight” vanishes. So I dug into the literature to see if this effect had been studied. And it turns out sports science has tested this idea in the lab.
1. Dickerson (2020): Disguised 1RM Trials
After establishing lifters’ one-rep max (1RM) on the bench press, researchers brought them back for three additional “disguised” trials:
Same as baseline (1RMEW),
+5% heavier (1RMIW),
–5% lighter (1RMDW).
The loads were camouflaged so participants couldn’t tell if they were lifting more, less, or the same.
Result: Lifters succeeded at weights they normally would have failed, purely because they didn’t know the bar was heavier.
2. Piper et al. (2023): False Feedback on Strength
On the leg press, participants were told they were lifting lighter loads than they actually were - in reality, 5–15% above their 1RM.
Result: They exceeded baseline strength when deceived about the load. However, deception also lowered future goal-setting: after the truth came out, participants aimed lower next time. The results were highly significant (p< 0.001).
Figure 1. Performance outcomes under feedback conditions in Piper et al. (2023).
TC (True Control): lifting at 1RM with accurate feedback.
TF (True Failure): attempting a load too heavy to lift, with accurate feedback.
T+5%, T+10%, T+15%: participants were told they were lifting 5%, 10%, or 15% lighter than the actual load; bars show the true amount lifted.
3. Wingate Tests: Deception and Anaerobic Power
In cycling sprints, researchers manipulated either the perceived resistance or the feedback about power output. When athletes thought they were pedaling at lower intensity, or saw inflated power feedback, they produced more output than with accurate information.
The Missing Parallel in Cognitive Science
So far we’ve seen that in strength and endurance sports, disguised loads and deceptive feedback can unlock hidden performance. But what about the mental gym? Has cognitive psychology tested the same idea - that believing a task is easier than it really is can boost immediate performance?
Surprisingly, not really.
Cognitive scientists have done plenty of work on task difficulty and expectancy effects, but in different forms:
They change the actual difficulty of tasks (e.g., harder stimuli or dual-task load) and show that performance worsens (Crittenden et al., 2012; Taylor & Thoroughman, 2008).
They study stereotype threat or “diagnostic” framing, where telling people a test is diagnostic of intelligence reduces performance (Steele & Aronson, 1995).
They manipulate expectations about training outcomes, not single-trial performance (Foroughi et al., 2016; Rabipour et al., 2018).
Or they give false feedback after performance (Grealy et al., 2019).
What seems missing is the exact same paradigm we saw in Dickerson’s bench-press study:
Tell participants beforehand that a task is easier (or harder) than it really is, without altering the task itself, and measure their immediate performance.
That gap matters. It suggests that sports science may actually be ahead of psychology in probing what I call the “mind adds weight” effect.
Proposed Cognitive Experiments
Sports science already shows that disguised loads change performance under the bar. To test whether the same “mind adds weight” effect exists in mental work, we can design two complementary experiments: one that mirrors George Dantzig’s homework story, and one that mirrors the bench press paradigm.
1. The Dantzig Analogy: General Difficulty Framing
Task: Logic puzzles or insight problems of moderate difficulty (solvable by ~50% of participants).
Manipulation:
Group A: told the puzzles are “very easy, most people solve them quickly.”
Group B: told the puzzles are “extremely difficult, almost nobody solves them.”
Group C: neutral instructions.
Outcomes: accuracy, time to first attempt, persistence, and self-rated difficulty.
Hypothesis: Just as Dantzig solved “unsolvable” problems because he thought they were homework, participants told the puzzles are easy will persist longer and perform better. No story of impossibility = no extra mental weight.
2) Bench-Press Analogy: Personalized Disguised Load
2a) Puzzles (calibrated)
Phase 1 (truthful): Calibrate individual difficulty (~60% solve rate).
Phase 2 (deceptive prompts on matched-difficulty items):
Light: “Next item is below your level.”
Heavy: “Next item is above your level.”
Neutral.
Outcomes: Accuracy, latency, quit/skip, strategy switches, hints; trial-by-trial exertion.
Hypotheses: Light ⇒ faster, higher solve rate, lower exertion; Heavy ⇒ opposite; effects strongest on first attempts.
2b) Working Memory (Dual N-Back / visual WM)
Why WM fits: Like %1RM, WM difficulty scales per person (N level or set size).
Phase 1 (truthful calibration):
Dual N-Back: find each participant’s threshold N (~70% accuracy).
Visual WM arrays: find set size with ~70% accuracy.
Phase 2 (deceptive, fixed at the calibrated difficulty):Light: “This block is below your baseline ability.”
Heavy: “This block is above your baseline ability.”
Neutral.
Keep difficulty constant at the calibrated N (or set size) to isolate expectancy. Avoid adaptive ladders here.
Outcomes: Accuracy, RT, d′, hit/false-alarm rates; block-end confidence and perceived effort.
Design notes (for both 2a & 2b):
Within-subject, counterbalanced prompts; 24–40 trials (or 3–4 WM blocks).
Pre-register exclusions (prior exposure, inattentive).
Ethics: mild deception + thorough debrief with option to withdraw data.
Sample: ~60–100 participants typically detects small–moderate expectancy effects (d ≈ .20–.35).
Materials:
Puzzles: RAT, matchstick arithmetic, Luchins water-jar (piloted to ~50–60% solve).
WM: standard Dual N-Back stimuli or change-detection arrays; fixed difficulty at each person’s calibrated level.
Prereg & funding note:
I’m happy to run this as a preregistered study (OSF) with open materials/code. If you have grant support for pilot work on expectancy effects, I’m open to collaboration.
References
Crittenden, B. M., & Duncan, J. (2014). Task difficulty manipulation reveals multiple demand activity but no frontal lobe hierarchy. Cerebral Cortex, 24(2), 532–540. https://doi.org/10.1093/cercor/bhs428
Dickerson, B. L. (2020). The effects of resistance deception on muscular strength and muscular endurance exercise (Master’s thesis, Stephen F. Austin State University).
Foroughi, C. K., Monfort, S. S., Paczynski, M., McKnight, P. E., & Greenwood, P. M. (2016). Placebo effects in cognitive training. Proceedings of the National Academy of Sciences, 113(27), 7470–7474. https://doi.org/10.1073/pnas.1601243113
Gieser, V. R., Droessler, J. T., Dixon, M. J., Wong, R. L., & Thorp, D. B. (2013). Effect of temporal deception on power output during a 30 s Wingate test. International Journal of Exercise Science: Conference Proceedings, 8(1), Article 7.
Grealy, M. A., Cummings, J., & Quinn, K. (2019). The effect of false positive feedback on learning an inhibitory-action task in older adults. Experimental Aging Research, 45(4), 346–356. https://doi.org/10.1080/0361073X.2019.1627494
Piper, T. J., Radlo, S. J., Gerhardt, R. T., Brooks, T. D., & Schnaiter, M. J. (2023). The effects of deception on maximal strength, goals, and physical self-efficacy. International Journal of Strength and Conditioning, 3(1), 1–13.
Shaabani Ezdini, E., Irandoust, K., & Taheri, M. (2025). The effects of deceptive intensities during Wingate testing on the anaerobic performance and fatigue index of male cross-country cyclists. International Journal of Body, Mind and Culture, 12(3), 155-165. https://doi.org/10.61838/ijbmc.v12i3.984
Steele, C. M., & Aronson, J. (1995). Stereotype threat and the intellectual test performance of African Americans. Journal of Personality and Social Psychology, 69(5), 797–811. https://doi.org/10.1037/0022-3514.69.5.797