Comparison of graphic symbol learning in individuals with aphasia and right hemisphere brain damage

Background

This study compared the differences in performance on acquisition and retention of Blissymbols across several learning trials by individuals with aphasia, individuals with right hemisphere brain damage, and neurologically normal adults. The comparative analysis of Blissymbol acquisition and retention profiles presented by individuals with aphasia and those with right hemisphere brain damage will further elucidate the role of right hemisphere in processing ideographic symbols. Additionally, Blisssymbols were selected in a manner, so that the effects of symbol translucency and complexity on the recognition and retention of graphic symbols could be examined. Blissymbols are conceptually based logographs that provide us a unique opportunity to assess the cognitive consequences of a non-phonetic symbol system in individuals with brain damage.

How did we teach?

A paired- associate learning paradigm was used to teach the 40 symbol-referent pairs to all three groups of subjects. Each subject participated in two experimental sessions. A total of four repeated blocks of trials were conducted with each subject in the first experimental session and three repeated blocks of trials were conducted during session 2. Subjects’ were requested to point at the drawing that matches the name examiner calls out. A correct response was acknowledged by a spoken affirmation. For an incorrect response, subjects were shown the correct response and symbol gloss was repeated by saying "Here is _____".

Who were the participants?

A total of 28 participants took part in this study. Participants with brain-damage were 18 right handed-adults, 8 with unilateral right hemisphere pathology and 10 with aphasia as a result of unilateral left hemisphere pathology. Ten neurologically healthy adults served as normal controls.

What outcomes did we monitor for whom?

We monitored and compared the ability of individuals with aphasia and individuals with right hemisphere brain damage to recognize and retain pictographic, ideographic, and opaque Blissymbols.

What did we find?

We found that individuals with aphasia and neurologically normal adults do not differ significantly in recognition and retention of Blissymbols. However, individuals with right hemisphere brain damage recognized and retained significantly fewer symbols compared to individuals with aphasia and normal adults. Further, transluceny was found to strongly influence the symbol recognition and retention. More high translucent symbols were recognized correctly than low translucent symbol by all groups. Complexity did not have any influence on the recognition of symbols.

What does this mean for practice?

The finding that individuals with aphasia can learn and retain Blissymbols has significant clinical implications for aphasia rehabilitation. Our results suggest that the undamaged right hemisphere in individuals with aphasia can be used to facilitate communication through graphic symbols. The finding that translucency has a facilitative effect on learning also has clinical implications. If the goal of aphasia therapy is to provide an immediate means of communication for individuals with severe and global aphasia, one should consider choosing initial lexical items that have a strong visual relationship between symbol and a referent, followed by low translucent symbols. Symbols that have no conceptual or visual relationship to their referent may be selected and taught later.