Neuropsychology
Three fictional profiles across six memory measures, and three claims about separable systems. For each claim on each profile there are three honest answers, and one of them is used more than the others.
Simulated — invented people, invented measures, invented control groups
By the end you should be able to say what a profile must contain before it supports a dissociation between memory systems.
About 15 minutes. Nothing you do here is saved or sent anywhere.
Invented profiles with invented numbers, written to make particular inferences possible or impossible. No real person, published case or clinical instrument is described, no syndrome is named, and nothing here diagnoses, assesses or gives a prognosis for anybody. Memory difficulty is described in terms of tasks, never as a description of a person.
A fictional person can repeat a list of digits back normally, and cannot recall a word list thirty minutes after learning it.
Nothing here changes the controls for you, and none of it says what you are going to find.
Claim 1 of 3
| Measure | What it asks for | Distance from controls | Standing |
|---|
A third of the grid cannot be settled by the profile in front of you. Profile A settles all three claims and is the only one that does; that is what makes it a textbook case rather than a typical one. A profile decides a distinction only when one measure is clearly below its controls while another, comparable one is clearly not - and "comparable" is doing a great deal of work in that sentence.
Evidence that two tasks come apart shows that they do not depend on all the same things. It does not show that there are two systems, that each has a location, or that either is a natural kind. The multiple-systems account of memory is a good theory supported by convergent evidence from many sources; no single profile establishes it, and the wording is worth keeping honest.
The pattern in profile C - recall at floor, recognition normal - is the one always cited for a difficulty at retrieval rather than at storage. It does not establish it, because recognition is the easier task: a memory trace too weak to be produced from nothing can still be strong enough to be picked out of two options. The two tasks would have to be matched for difficulty in healthy people before the comparison meant what it appears to mean, and matching them is genuinely hard.
Profile D is impaired on every verbal measure, including word knowledge. Its episodic scores are therefore not readings of episodic memory: they are readings of episodic memory for material the person no longer knows well. And the one intact measure - skill learning - differs from the impaired ones in system and in material and response, so even that contrast cannot be pinned on the distinction it appears to show.
Profile E is mildly below controls on everything and selectively below on nothing. Reduced effort, fatigue, poor sleep, pain, medication, low mood, anxiety about being tested, a language other than the one being tested in, uncorrected hearing, and simply having a lower starting point than the control group all produce that shape. So does a genuine general slowing. Nothing in the profile chooses between them, and reaching for a memory system is the least well-supported move available.
None of this page mentions anatomy, on purpose. The distinctions these profiles bear on are between what tasks require, not between structures. Structures matter, and the mapping between a profile and a structure is many-to-many. The same profile follows damage in several places, and damage in one place produces several profiles depending on extent, connections and what else went with it.