Project Summary
Dyslexia is a learning disorder that impairs reading in childhood and throughout life. This is, at least in part,
because of language-related problems in dyslexia. However, it is currently unclear if dyslexia is solely a
language-based disorder or if there are other deficits as well. When dyslexic individuals read, their eye
movements differ from readers without dyslexia, indicating decreased visual attention efficiency. More
specifically, research suggests that dyslexic readers have a narrower ‘attentional spotlight’ when they read,
meaning that they extract useful information from a smaller section of the text than do typical readers. This
deficit in visual attention may be caused by an underlying language deficit or may be partly independent of the
language deficit – the current literature is unclear. The purpose of this research is to reveal whether visual
attention deficits are independent of language deficits in dyslexia or not. This will be accomplished by
comparing eye movements (which reflect visual attention) in reading and in visual tasks, such as memorizing a
picture or searching for an object in a photograph, that do not involve language. A group of adult participants
with dyslexia and a group of control participants will perform these tasks while their eye movements are
monitored. In the first experiment, visual information will be restricted using a ‘moving window’ of different
sizes. This technique helps define the size of the attentional spotlight, which is the smallest window that causes
no change in eye movements compared to a no-window control condition. If the visual attention deficit in
dyslexia is not entirely caused by the language deficit, then visual attention problems should be apparent, in the
form of a narrower attentional spotlight, in the language-free tasks as well as in reading. On the other hand, if
the visual attention deficit is solely caused by the language deficit, then the eye movements of dyslexics should
only differ from controls in the reading task. These same participants will also perform reading and scene
memorization tasks while their eyes are tracked and their brains are being scanned (fMRI) in order to identify
the cortical network involved in visual attention and the specific brain regions within this network that are
impaired in dyslexia. If dyslexia is primarily a language disorder, then only reading-specific cortical areas
should be differentially active in dyslexic participants, and no activation differences should be observed during
the scene memorization task. Finally, these eye-tracking and neuroimaging data will be used in combination
with scores on a battery of standardized language tasks to identify which aspects of language (phonology,
vocabulary, fluency) are predictive of visual attention and to quantify the extent to which attentional problems
in dyslexia are dependent on language deficits. This knowledge will help focus interventions and treatments for
dyslexia.