Using transitional information in sign and gesture perception.

For sign languages, transitional movements of the hands are fully visible and may be used to predict upcoming linguistic input. We investigated whether and how deaf signers and hearing nonsigners use transitional information to detect a target item in a string of either pseudosigns or grooming gestures, as well as whether motor imagery ability was related to this skill. Transitional information between items was either intact (Normal videos), digitally altered such that the hands were selectively blurred (Blurred videos), or edited to only show the frame prior to the transition which was frozen for the entire transition period, removing all transitional information (Static videos). For both pseudosigns and gestures, signers and nonsigners had faster target detection times for Blurred than Static videos, indicating similar use of movement transition cues. For linguistic stimuli (pseudosigns), only signers made use of transitional handshape information, as evidenced by faster target detection times for Normal than Blurred videos. This result indicates that signers can use their linguistic knowledge to interpret transitional handshapes to predict the upcoming signal. Signers and nonsigners did not differ in motor imagery abilities, but only non-signers exhibited evidence of using motor imagery as a prediction strategy. Overall, these results suggest that signers use transitional movement and handshape cues to facilitate sign recognition.