Experiment 1
The primary aim of this experiment was to dissociate
between crossmodal and verbal demands in driving PAL
deficits in dyslexia. To do so, we tested the following PAL
mapping conditions: visual–verbal, verbal–verbal, visual–
visual, and verbal–visual. We predicted that if PAL deficits
reflect crossmodal associative learning, deficits should
emerge in both visual–verbal and verbal–visual PAL. On
the contrary, if PAL deficits are a consequence of verbal
deficits, impaired performance should emerge in both visual–
verbal and verbal–verbal PAL. As outlined above,
underlying phonological deficits are likely to lead to poor
performance on any PAL task with significant verbal demands.
Thus we might expect verbal–verbal PAL to be impaired
as a consequence of underlying phonological
deficits. However, these demands may not fully account
for PAL deficits in dyslexia; crossmodal demands may pose
an additional and specific constraint on PAL performance.
In this case, we would expect impairments in visual–verbal,
verbal–visual, and verbal–verbal PAL. Note that
although such a finding would implicate both verbal and
crossmodal demands in poor PAL performance, it would
still provide support for deficient crossmodal learning in
dyslexia.