Description of Routes in People With Intellectual Disability.

Courbois et al. (2019) asked adults with intellectual disability to describe a familiar walking route. They also tested the same adults on silent tasks: pointing to landmarks and placing items on a blank map.

The team compared the two data sets to see if weak spoken directions meant weak spatial memory.

Spoken directions were short and action-heavy: "Go left, then straight, then right." Landmark names were rare.

On the silent tasks the same adults pointed accurately to unseen landmarks and placed most items in the correct map spots. Words looked poor; knowledge was intact.

Lacombe et al. (2024) extends this idea. They showed that students with ID express nearly one-third of their spatial knowledge through hand gestures, not speech. Together the papers say: check hands, maps, or pointing before you label a client "lost."

Van der Molen et al. (2010) seems to disagree at first. They found that adults with ID plus psychosis give even shorter procedural explanations than ID-only peers. The gap is real, but it sits on top of the same language-masking issue Yannick found. More diagnoses, more masking.

Earl et al. (2019) used eye tracking in a shared street zone and saw that adults with ID look at traffic clues only two-thirds as often as neurotypical adults. Combine this with Yannick and you get a full picture: clients may know the landmarks, yet still miss the critical visual cues while walking.

If you rely on spoken route recall during assessments, you risk underestimating spatial memory. Swap in landmark pointing, map placement, or gesture-friendly tasks. The same client who says "I don’t know" may quietly point the right way.