Temporal processing and delay discounting

The research behind "I have plenty of time" — narrator: they did not.

What the essay claims

"Time blindness is the ADHD experience of time as binary: there's now, and there's not now. […] Add chronically optimistic time estimates (packing feels like a twenty-minute job; it's an evening) and the night-before panic isn't a character flaw."

The construct

"Time blindness" is a popularisation. It is not a term in the research literature, and there is no body of work under that name. What exists instead is two separate research programs, and the essay's paragraph draws on both without distinguishing them.

Temporal processing — also called time perception — is measured with four standard paradigms: discriminating which of two intervals was longer, estimating how long an interval lasted, producing an interval of a stated length, and reproducing one just experienced. These paradigms operate on milliseconds to a few seconds.

Delay discounting is the rate at which a reward loses value as it moves further into the future. It is the closest measured construct to "there's now and there's not now," and it is the more robust of the two.

The gap to keep in view: the essay is about days. The research is about seconds.

What the research says

• Across 824 effect sizes spanning the lifespan, time-perception deficits in ADHD showed a mean g = 0.688, moderated by the age of the sample and by working memory; in separate analyses, the working-memory link applied only to samples under 18 and an effect of ADHD subtype only to samples 18 and over. (Metcalfe, McFeaters & Voyer, 2024)
• Across 55 studies, people with ADHD had more difficulty discriminating very brief durations, especially in the sub-second range, more variability in estimating durations of several seconds, and deficits in time estimation and production accuracy that the authors read as "indicative of an accelerated internal clock." (Marx et al., 2022)
• Across 27 studies of children and adolescents (1,620 with ADHD, 1,249 controls), participants with ADHD perceived time less accurately (Hedges' g > 0.40) and less precisely (g = 0.66), with a higher tendency to overestimate time. (Zheng et al., 2022)
• Across 25 case-control comparisons from 21 investigations (total N = 3,913), monetary delay discounting was elevated in ADHD with a medium effect size, d = 0.43, with no significant moderation by sample age (under 18 versus over 18), by whether rewards were real or hypothetical, or by comorbid conduct or oppositional defiant disorder, and with minimal heterogeneity and minimal evidence of publication bias. (Jackson & MacKillop, 2016)
• People systematically underestimate how long their own tasks will take — the "planning fallacy" — a finding established in the general population. (Buehler, Griffin & Ross, 1994)

What it doesn't say

The timing research does not measure anything on the timescale the essay is about. Discriminating a 400-millisecond tone from a 500-millisecond tone is a long way from failing to feel that a trip is four days away. No study I found tests whether future events feel less real to people with ADHD at the scale of days, and nothing on this page should be read as evidence that they do. That part of the essay is experience, and is now labeled as experience.

One finding points the opposite way from the essay, read carelessly. Zheng et al. found a tendency to *over*estimate durations, while the essay describes *under*estimating how long packing will take. These are not actually in conflict — judging how long a presented interval lasted and predicting how long a future task will take are different measures — but the distinction matters, and it is the reason the lab findings cannot be used to support the twenty-minutes-became-four-hours story.

The planning fallacy is not an ADHD finding. Buehler et al. demonstrated it in the general population; underestimating your own task durations is an ordinary human trait. I searched for research on task-duration prediction specifically in ADHD and found none. If the effect is larger in ADHD — which would be the interesting claim — that has not been shown, and the essay no longer implies it.

Much of the timing literature is paediatric. Zheng et al. is explicitly children and adolescents. Metcalfe et al. covers the lifespan and finds age to be a moderator, which is itself a reason not to read child findings as adult findings.

Delay discounting is the strongest result here, and it is narrower than it sounds. It measures preference for a smaller reward now over a larger one later. That is a real and well-replicated group difference that holds for adults, but preferring the sooner reward is not the same thing as being unable to perceive a deadline approaching.

How this shaped the app

The app does not try to change anyone's sense of time; it puts the sequence into the structure, so that lead-time tasks sit in a Prep phase that exists days before the suitcase does, and the tab bar tracks where the trip actually is. Days on the Plans rail carry real weekday names rather than numbers.

The decisions this shaped — the five phases and the homeward leg — are on Why the app is built this way.

The app has no alarms, timers or notifications, and that is a design position rather than a research finding. An app that interrupts is an app you mute. You are entitled to disagree with that, and no study on this page is being used to defend it.

Sources

• Metcalfe KB, McFeaters CD, Voyer D (2024). Time-perception deficits in attention-deficit/hyperactivity disorder: a systematic review and meta-analysis. Developmental Neuropsychology 49(1):1–24. doi:10.1080/87565641.2023.2293712
• Marx I, Cortese S, Koelch MG, Hacker T (2022). Meta-analysis: altered perceptual timing abilities in attention-deficit/hyperactivity disorder. Journal of the American Academy of Child & Adolescent Psychiatry 61(7):866–880. doi:10.1016/j.jaac.2021.12.004
• Zheng Q, Wang X, Chiu KY, Shum KK-M (2022). Time perception deficits in children and adolescents with ADHD: a meta-analysis. Journal of Attention Disorders 26(2):267–281. Children and adolescents only. doi:10.1177/1087054720978557
• Jackson JNS, MacKillop J (2016). Attention-deficit/hyperactivity disorder and monetary delay discounting: a meta-analysis of case-control studies. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging 1(4):316–325. Open access. doi:10.1016/j.bpsc.2016.01.007
• Buehler R, Griffin D, Ross M (1994). Exploring the "planning fallacy": why people underestimate their task completion times. Journal of Personality and Social Psychology 67(3):366–381. General population, not ADHD. doi:10.1037/0022-3514.67.3.366