Does psychosis weaken memory, confidence judgments or effort?
People with psychosis or more psychotic-like experiences remembered shapes less precisely, but they judged their own memory accurately and put as much effort into searching as everyone else.
Source
Psychosis and Psychotic-Like Symptoms Affect Cognitive Abilities but Not Motivation in a Foraging Task
Study at a glance
- Design
- Cross-sectional — Study 1 correlated questionnaire-measured psychotic-like symptoms with task performance in healthy adults; Study 2 compared first-episode psychosis patients with age- and gender-matched controls on the same visual memory-and-search task and neurocognitive tests.
- N
- Study 1: 52 healthy adults. Study 2: 46 participants (23 patients with psychosis, 23 matched healthy controls). No single pooled N is reported for the main analyses.
- Population
- Norwegian healthy adults (Study 1) and patients with a first episode of psychosis recruited from the TIPS early-intervention study plus matched controls (Study 2)
- Outcome
- Error in visual short-term memory, size of a self-drawn capture area relative to that error (metacognitive calibration), search perseverance on trials with no target, latency and vigor of searching, plus Trail Making and digit-symbol test scores
Structured fields used in claim comparison tables when every cited study has a complete layer.
What they did
Participants played a computer game in which they memorised a shape, picked its location on a ring of 30 similar shapes, drew an area around their choice big enough to be sure it contained the target (an implicit confidence judgment), and then clicked to search for a nut that a squirrel sometimes secretly stole. In Study 1, 52 healthy adults also filled in a questionnaire on psychotic-like, negative and depressive experiences. In Study 2, 23 patients with psychosis and 23 matched controls did the same task, with patients' symptoms rated by interview. Everyone also completed Trail Making and digit-symbol tests of processing speed and flexibility.
What they found
In healthy adults, more positive psychotic-like experiences went with larger memory errors and fewer digit-symbol pairings, and patients were slower on both Trail Making tests and had larger memory errors than controls. Confidence was well calibrated in everyone: the capture area matched actual memory error regardless of symptoms or diagnosis. Both patients and controls searched beyond their own capture area and searched less when success was less likely, with no group difference in perseverance, search cost, latency or vigor. In healthy adults only, people reporting more symptoms gave up search somewhat sooner.
The limits
What it doesn't show
Both samples were small, and the authors say they lacked power to detect subtle motivational differences or subgroups of patients with low motivation. Symptoms were measured with a self-report questionnaire in Study 1 but a clinical interview in Study 2, so the two studies cannot be compared directly. Patients came from an early-intervention programme and may have had relatively mild negative symptoms, which could explain why effort looked normal. The available text omits the introduction and the first stage of the task and the Study 1 recruitment details, and the design is correlational, so it cannot show that symptoms cause the memory deficits.
Key terms
- Metacognition
- Knowing how good your own thinking or memory is; here, how well the size of the drawn capture area matched a person's real memory error.
- Psychotic-like experiences
- Milder, non-clinical versions of psychosis symptoms, such as unusual perceptions or beliefs, that occur in the general population.
- Positive vs negative symptoms
- Positive symptoms add experiences (hallucinations, delusions); negative symptoms remove normal functions (low motivation, flat emotion, withdrawal).
- Perseverance score
- How far someone kept searching on no-target trials relative to their own capture area; above 1 means they searched further than their confidence implied.
- Vigor
- The speed with which someone makes search clicks, used as an index of how much they value the reward.
- Effort-based decision-making
- Choosing how much effort to invest in pursuing a goal given its value and the chance of success.
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Quiz yourself
What did the size of the drawn capture area represent in this task?
Common questions
Why measure confidence by drawing an area instead of asking for a rating?
The drawn area is a behavioural, implicit confidence judgment with points at stake, so it avoids some biases of verbal rating scales and can be compared directly with actual memory error.
Does this mean people with psychosis have no motivation problems?
No. It shows that on this particular task effort looked normal; the samples were small and patients had relatively few negative symptoms, so real-world motivational difficulties could still exist.
If patients remembered worse, how could their search costs be the same?
The cost measure accounts for each person's own belief about their error and the probability of success, so patients searched longer in absolute terms but invested effort in the same proportion to what they believed.
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