Gesturing appears to be integral to the speaking process and may reflect or even facilitate the thinking that underlies speaking. One popular theory holds that gesturing is a learned behavior. Iverson and Goldin-Meadow decided to test this theory by comparing two groups of 12 children, one in which the children could see and the other in which the children were congenitally blind. The median age of the children was 11˝.
Each child was given two glasses containing equal amounts of water. The water from one glass was poured into a shallow, wider dish. The children were then asked whether there was the same amount of water in the dish as in the glass, and to justify their answers. The blind children were allowed to examine the containers with their hands throughout the experiment. “It’s the kind of task that really gets kids’ thinking and reasoning process going,” Iverson explains. “They have to be engaged when they’re coming up with an answer.”
The study found that all 12 blind speakers gestured as they spoke, despite having never seen a gesture. The blind group gestured at a rate that was not reliably different from that of the sighted group and conveyed the same information using the same range of gestures. “In this task, the kids tended to make a lot of gestures related to the height of the containers,” Iverson says. “They also held their hands apart at different distances to indicate that one container was wide and another skinny, or they would gesture as if they were pouring the contents of one container into another.”
Iverson hypothesized that speakers may gesture because they understand gestures can convey useful information to the listener. To test this hypothesis, she and Goldin-Meadow ran the same experiment with another group of blind children and included listeners that the speakers knew were also blind. The blind speakers gestured to blind listeners at a rate not reliably different from that of the other groups.
“The question I’m pursuing now is, what exactly does gesturing do to the process of thinking and speaking?” says Iverson. “I’m currently running a study that looks at what happens when you ask people to not gesture at all, measuring the effects of inhibiting gesture on performance in a memory task. The results should provide a better understanding of what gesturing can tell us about the basic nature of thought.”
In this study, adults are asked to watch a cartoon they’ve never seen before. They then explain what happened in the cartoon to a listener who hasn’t seen it. Members of one group are asked to sit on their hands while they explain the events of the cartoon; members of another group are allowed to gesture freely. All members of the study return exactly one week later and are asked to retell the events of the cartoon to a listener.
Although still a work in progress, Iverson has so far found that “the people who are not allowed to gesture on their first visit perform much worse on the second visit in terms of how much of the cartoon they recall and how accurate the information is that they convey.” Iverson’s initial conclusions are that gesturing and memory are closely linked.
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