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Hack 61. Talk to Yourself
Language isn't just for talking to other people; it may play a vital role in helping your brain combine information from different modules. Language might be an astoundingly efficient way of getting information into your head from the outside [Hack #49] , but that's not its only job. It also helps you think. Far from being a sign of madness, talking to yourself is something at the essence of being human. Rather than dwell on the evolution of language and its role in rewiring the brain into its modern form,1 let's look at one way language may be used by our brains to do cognitive work. Specifically we're talking about the ability of language to combine information in ordered structuresin a word: syntax. Peter Carruthers, at the University of Maryland,2 has proposed that language syntax is used to combine, simultaneously, information from different cognitive modules. By "modules," he means specialized processes into which we have no insight,3 such as color perception or instant number judgments [Hack #35] . You don't know how you know that something is red or that there are two coffee cups, you just know. Without language syntax, the claim is, we can't combine this information. The theory seems pretty boldor maybe even wrongbut we'll go through the evidence Carruthers uses and the details of what exactly he means and you can make up your own mind. If he's right, the implications are profound, and it clarifies exactly how deeply language is entwined with thought. At the very least, we hope to convince you that something interesting is going on in these experiments. 5.10.1. In ActionThe experiment described here was done in the lab of Elizabeth Spelke.4 You could potentially do it in your own home, but be prepared to build some large props and to get dizzy. Imagine a room like the one in Figure 5-4. The room is made up of four curtains, used to create four walls in a rectangle, defined by two types of information: geometric (two short walls and two long walls) and color information (one red wall). Figure 5-4. Setup for Spelke's experimentsa rectangular room with one colored wallNow, think about the corners. If you are using only geometric information, pairs of corners are identical. There are two corners with a short wall on the left and a long wall on the right and two corners the other way around. If you are using only color information, there are also two pairs of identical corners: corners next to a red wall and corners not next to a red wall. Using just one kind of information, geometry or color, lets you identify corners with only 50% accuracy. But using both kinds of information in combination lets you identify any of the four corners with 100% accuracy, because although both kinds of information are ambiguous, they are not ambiguous in the same way. So, here's a test to see if people can use both kinds of information in combination.5 Show a person something he'd like, like some food, and let him see you hide it behind the curtains in one corner of the room. Now disorient him by spinning him around and ask him to find the food. If he can combine the geometric and the color information, he'll have no problem finding the foodhe'll be able to tell unambiguously which corner it was hidden in. If he doesn't combine information across modules, he will get it right 50% of the time and 50% of the time wrong on his first guess and need a second guess to find the food. Where does language come into it? Well, language seems to define the kinds of subjects who can do this task at better than 50% accuracy. Rats can't do it. Children who don't have language yet can't do it. Postlinguistic children and adults can do it. Convinced? Here's the rub: if you tie up an adult's language ability, her performance drops to close to 50%. This is what Linda Hermer-Vazquez, Elizabeth Spelke, and Alla Katsnelson did.6 They got subjects to do the experiment, but all the time they were doing it, they were asked to repeat the text of newspaper articles that were played to them over loudspeakers. This "verbal shadowing task" completely engaged their language ability, removing their inner monologue. The same subjects could orient themselves and find the correct corner fine when they weren't doing the task. They could do it when they were doing an equivalently difficult task that didn't tie up their language ability (copying a sequence of rhythms by clapping). But they couldn't do it with their language resources engaged in something else. There's something special about language that is essential for reorienting yourself using both kinds of information available in the room. 5.10.2. How It WorksPeter Carruthers thinks that you get this effect because language is essential for conjoining information from different modules. Specifically he thinks that it is needed at the interface between beliefs, desires, and planning. Combining across modalities is possible without language for simple actions (see the other crossmodal hacks [Hack #57] through [Hack #59] in this book for examples), but there's something about planning, and that includes reorientation, that requires language. This would explain why people sometimes begin to talk to themselvesto instruct themselves out loudduring especially difficult tasks. Children use self-instruction as a normal part of their development to help them carry out things they find difficult.7 Telling them to keep quiet is unfair and probably makes it harder for them to finish what they are doing. If Carruthers is right, it means two things. First, if you are asking people to engage in goal-oriented reasoning, particularly if it uses information of different sorts, you shouldn't ask them to do something else that is verbal, either listening or speaking.
Second, if you do want to get people to do complex multisequence tasks, they might find it easier if the tasks can be done using only one kind of information, so that language isn't required to combine across modules. 5.10.3. End Notes
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