Hemispheric processing of idioms: The influence of familiarity and ambiguity

• We explored hemispheric processing of idioms (high versus low familiarity; high versus low ambiguity).
• Using divided visual field, participants read idiomatic texts and viewed related target words.
• We observed left hemisphere advantages for high and low familiarity and low ambiguity idioms.
• We also observed a right hemisphere advantage for high ambiguity idioms.
• We conclude that the hemispheres process idioms differently based on the level of idiom ambiguity.

Recent findings suggest that the right hemisphere plays a key role when readers comprehend figurative language. However, it is currently unclear how specific types of figurative language, such as idioms (e.g., “to bury the hatchet”), are processed in the right and left cerebral hemispheres. Prior research suggests that a reader's previous exposure to an idiomatic phrase (i.e., the level of familiarity) and the plausibility of an idiom (i.e., the level of ambiguity) influence how idioms are processed. To investigate how familiarity influences the hemispheric processing of idioms (Experiment 1), participants read texts containing familiar or less familiar idioms and made lexical decisions to related target words presented to the left visual field-right hemisphere or to the right visual field-left hemisphere. To investigate how ambiguity influences the hemispheric processing of idioms (Experiment 2), participants read texts containing high or low ambiguity idioms and completed a lexical decision task to related target words presented to each visual field-hemisphere. For both familiar and less familiar idioms, greater facilitation was evident in the left hemisphere than in the right hemisphere. Additionally, greater facilitation was evident in the left hemisphere for low ambiguity idioms than for high ambiguity idioms, and greater facilitation was evident in the right hemisphere for high ambiguity idioms than for low ambiguity idioms. These findings suggest that the right hemisphere has an advantage when readers process ambiguous idioms, whereas the left hemisphere has an advantage when readers process low ambiguity idioms, and both familiar and less familiar idioms.