The isomorphic mapping hypothesis: evidence from Korean

This paper evaluates the relative merits of the trace deletion hypothesis, which attributes agrammatic comprehension difficulties to the loss of traces, and the isomorphic mapping hypothesis, which proposes that agrammatics have difficulty understanding sentences in which there is a nonisomorphic mapping between the syntactic representation and the corresponding event in the real world. (The two are isomorphic if the order of NPs reflects the place of entities in the event's 'action chain.' Since agents act on themes and transmit them to goals, the agent-theme-goal order is isomorphic with the corresponding event but the agent-goal-theme order is not.) The two hypotheses contrast in the predictions they make concerning goal-theme and theme-goal patterns in Korean: the TDH predicts degraded performance on the theme-goal structure (which is derived from the goal-theme structure); the IMH predicts difficulties on the goal theme structure, since it is nonisomorphic. Results of a comprehension study involving four Korean Broca's aphasics provide strong support for the IMH over the TDH.