Enhanced performance on a sentence comprehension task in congenitally blind adults

Abstract

People born blind habitually experience linguistic utterances in the absence of visual cues and activate "visual" cortices during sentence comprehension. Do blind individuals show superior performance on sentence processing tasks? Congenitally blind (n=25) and age and education matched sighted (n=52) participants answered yes/no who-did-what-to-whom questions for auditorily-presented sentences, some of which contained a grammatical complexity manipulation (long-distance movement dependency or garden path). Short-term memory was measured with a forward and backward letter-spans. A battery of control tasks included two speeded math tasks and vocabulary and reading tasks from Woodcock Johnson III. The blind group outperformed the sighted on the sentence comprehension task, particularly for garden-path sentences, and on short-term memory span tasks, but performed similar to the sighted on control tasks. Sentence comprehension performance was not correlated with span performance, suggesting independent enhancements.

Keywords: Sentence processing; blindness; garden path; plasticity; practice.

Figure 1.

Mean accuracy (left) and response times (right) for sighted and blind participants in syntactic movement (Move), matched non-movement (No-Move), garden path (GP) and matched non-garden path (No-GP) sentences. Error bars reflect SEM.

Figure 2.

Mean accuracy of sighted and blind participants in Woodcock-Johnson III measures—Word Letter Identification (WD-ID), Word Attack (WD-ATTCK), Synonyms (SYN), Antonyms (ANT), and Analogies (ANT), arithmetic—subtraction (SUB) and division (DIV), and short-term memory span—forward (FWD) and backward (BWD). Error bars reflect SEM.

Figure 3.

Correlation plots showing relationship between each participants’ mean performance on forward and backward letter span (% correct) and accuracy at answering comprehension questions for each of the sentence conditions (% correct, move, no move, garden path, no garden path). Sighted (top) and blind (bottom). No significant relationship between letter span and sentence processing performance was observed.

Figure 4.

Correlation plots showing significant relationship between each participants’ performance on garden-path sentences and movement sentences (left) and a significant relationship between each participants’ performance on forward and backward span tasks (right). Sighted (top) and blind (bottom).