Intelligibility and comprehension of time compressed sign language narratives

A method of time compressing visual displays was devised to assess the effects of compression on the comprehension of American sign language (ASL). Two ASL narratives were visually presented to three groups of deaf ASL users. A compression group was presented narratives compressed to 50% of the duration of the normal rates. A no-compression group was presented narratives signed at normal rates. A pause groups was presented compressed narratives with blank pauses inserted so that the total time per narrative was equal to that of the no-compression versions. Following each narrative, subjects completed a written comprehension task. Comprehension in both compression and pause groups was significantly lower than in the no-compression group. Pauses did not significantly affect scores relative to compression. An additional group of deaf ASL users was presented an intelligibility task in which signs taken from the narratives were presented in isolation either with or without compression. The total number of signs correctly identified was significantly lower with compression. Decrements in comprehension were best explained as the result of cumulative decrements in sign intelligibility and not as the result of decrements in available processing time.