Profiles of visual perceptual functions in Down syndrome.

Yi-To et al. (2015) gave the TVPS-3 visual-perception test to three groups: Down syndrome, intellectual disability, and typically developing kids.

They wanted to see if Down syndrome creates a unique visual-perception profile or looks like general ID.

Both Down syndrome and ID groups scored the same on every TVPS-3 sub-test.

Both groups landed far below the typically developing kids.

In short, Down syndrome does not add extra visual-perception problems beyond general ID.

Wan et al. (2017) extends these findings. After showing the baseline deficit here, they trained the same kids with a computer visual-perception game and scores went up.

Costanzo et al. (2013) used the same three-group design but tested executive functions. They found Down syndrome does show unique deficits in shifting and verbal inhibition, so the "no-unique-deficit" rule only holds for visual perception.

Bhaumik et al. (2009) looks like a contradiction at first—they claim a special simultaneous-working-memory weakness in Down syndrome. The tasks differ: TVPS-3 measures perception, while their study taxed memory for multiple spatial locations at once. Different constructs, different answers.

When you assess a client with Down syndrome, expect low TVPS-3 scores that match general ID norms. Use the same perception goals you would for any ID, and feel free to borrow the computerized training from Wan et al. (2017) if you need an evidence-based intervention.