Prospective memory and working-memory maintenance

The research behind Things that go into the suitcase stop existing.

What the essay claims

"'Object permanence' is the community's shorthand for it — not the infant-development milestone, but the everyday adult experience that things outside your visual field lose their grip on your attention entirely."

The construct

The popular term and the research term are different things, and this is the page that says so.

Object permanence is a real term with a fixed meaning: it is the understanding that an object continues to exist when you can no longer perceive it. It comes from Piaget's account of infant development, and it is studied in babies — there is experimental evidence for it in infants as young as five months (Baillargeon, Spelke & Wasserman, 1985). It is a capacity children acquire. It is not a capacity adults lose, and there is no literature describing adults with ADHD losing it.

So when the essay next door uses the phrase, it is borrowing a term of art to name a different experience. That's a fair thing for a community to do — the phrase describes the feeling exactly, which is why people reach for it — and the essay says outright that it doesn't mean the infant milestone. But this page is the one that has to be precise, so: the two research constructs that actually bear on "I packed it and now I can't believe I packed it" are prospective memory (remembering to carry out an intention you formed earlier) and working-memory maintenance (keeping something available while you do something else).

Naming those honestly costs something, because as the next section shows, they support the essay less tidily than the borrowed phrase would have.

What the research says

• Object permanence has been demonstrated experimentally in infants around five months of age; it is a construct from infant cognitive development. (Baillargeon, Spelke & Wasserman, 1985)
• In 45 adults with ADHD not taking stimulant medication, compared with 45 matched controls on a complex prospective-memory paradigm, the impairment was concentrated in task planning, with "only negligible to small effects" for plan recall, self-initiation and execution. (Fuermaier et al., 2013)
• In that same study, inhibition was the cognitive function that significantly predicted task planning performance. (Fuermaier et al., 2013)
• Across the six studies of prospective memory in children with ADHD identified in a systematic review, the majority found a deficit in time-based prospective memory but not in event-based prospective memory, with the underlying mechanism unresolved. (Reviewed in Talbot, Müller & Kerns, 2018)
• Working memory is among the domains with the most consistent group differences in ADHD (Willcutt et al., 2005), and moderate-magnitude differences persist into adulthood across both the phonological and the visuospatial domain (Alderson et al., 2013).
• Storing an intention in an external prop rather than in memory is, in the words of a review of the area, "highly effective." (Reviewed in Gilbert et al., 2023)

What it doesn't say

The research does not say that people with ADHD forget what they packed because it is out of sight. That is the essay's claim and it is a lived and community claim, not a finding. I went looking for the study that measures it and there isn't one.

The best adult prospective-memory evidence points at a different stage of the process than the essay does. Fuermaier et al. broke prospective memory into four components and found the deficit in planning the task — not in recalling the plan, initiating it, or executing it, where effects were negligible to small. The essay's story is about an intention decaying after it was formed. The measured failure is at the point the intention is formed. Those are not the same mechanism, and this page is not going to pretend the study supports the essay more closely than it does.

The child literature is thin and points somewhere narrower again. Six studies is a small evidence base for a review to draw on, they are studies of children rather than adults, and the deficit they mostly found was in time-based prospective memory ("do this at 4pm") rather than event-based ("do this when you see the suitcase"). Packing cues are largely event-based — the kind the reviewed studies did not find impaired.

Working-memory maintenance is the better-supported half of this page, and it is doing most of the actual work. The same limits apply as on the working memory page: the adult effect sizes are described rather than published, deficits are not detected uniformly, and none of the tasks resemble packing.

The offloading finding is from the general population, not from ADHD samples, and it describes reminders and calendars rather than checklists in a packing app.

How this shaped the app

The app assumes you will want to be sure twice and builds the second look in, rather than leaving you to re-open the bag: items can be flagged critical, and on the day of travel a computed Double Check section gathers every critical item into one list at the bottom of the phase, with a confirmation tick that is deliberately separate from the "packed" tick. Section and phase counts report what is left rather than what is done. The Return phase treats the journey home as a second packing event with its own reset.

The decisions this shaped — Double Check, critical items and the homeward leg — are on Why the app is built this way. The homeward leg is a design position rather than a research claim, and stays one.

Sources

• Baillargeon R, Spelke ES, Wasserman S (1985). Object permanence in five-month-old infants. Cognition 20(3):191–208. Cited to establish what object permanence means in the literature. doi:10.1016/0010-0277(85)90008-3
• Fuermaier ABM, Tucha L, Koerts J, Aschenbrenner S, Westermann C, Weisbrod M, Lange KW, Tucha O (2013). Complex prospective memory in adults with attention deficit hyperactivity disorder. PLoS ONE 8(3):e58338. Open access. doi:10.1371/journal.pone.0058338
• Talbot K-DS, Müller U, Kerns KA (2018). Prospective memory in children with attention deficit hyperactivity disorder: a review. The Clinical Neuropsychologist 32(5):783–815. Review article — children, not adults. doi:10.1080/13854046.2017.1393563
• Alderson RM, Kasper LJ, Hudec KL, Patros CHG (2013). Attention-deficit/hyperactivity disorder (ADHD) and working memory in adults: a meta-analytic review. Neuropsychology 27(3):287–302. doi:10.1037/a0032371
• Willcutt EG, Doyle AE, Nigg JT, Faraone SV, Pennington BF (2005). Validity of the executive function theory of attention-deficit/hyperactivity disorder: a meta-analytic review. Biological Psychiatry 57(11):1336–1346. doi:10.1016/j.biopsych.2005.02.006
• Gilbert SJ, Boldt A, Sachdeva C, Scarampi C, Tsai P-C (2023). Outsourcing memory to external tools: a review of "intention offloading." Psychonomic Bulletin & Review 30(1):60–76. Open access. Review article — general population, not ADHD. doi:10.3758/s13423-022-02139-4