[SOUND] One metaphor people have used is the idea of a language switch. It would be very difficult for us to always have more than one language in our head. And so what we need to accomplish is to be in the right langauge at the right time. Now, earlier I explained this idea of the context. So this last weekend somebody asked me about the nature of dreaming. And, of course, it's very difficult for us to know exactly what we dream. Right? Nobody can look in our heads and actually observe our dreams, only we can, and that's when we wake up, we remember pieces of it. But his point was, well how do I know what language I'm dreaming in? How do I control that? And I said most likely what happens is that your dreams are associated with certain people and places. And those people, and those places, are associated with certain languages. So, you're unlikely to dream about being at the, in the DMV in Nebraska speaking Spanish. And he, of course, answered, well, I don't really dream about being in the DMV in the, in Nebraska. I said well but, yes of course you don't, I'm using this extreme example but if you did, you probably wouldn't dream about speaking Spanish there. You most likely would think about it in English. And so the point is that we have an association between a language and a place or a language and a person. Now, the issue of language switching is interesting because people can change what language they're going to use. And so when that happens, what mechanisms are involved? Ed Penfield is very famous for his work with neurological mapping, mapping of brain areas and function. Came up with the idea of a switch and he then adapted this idea to think about language switching. Now these are old ideas from the 30s, 40s, 50s. The idea of language switching has had various lives since then. Right, since the time of Putzel] in the 20s, to Penfield talking about language switching, to then in the 60s more sophisticated types of studies looking at switching between languages, finally work in the 90s, which considered this. And then more recent work in the 2000s and even up until the present, 2014, that has looked at language switching within the brain. In 1997 Von Studnitz and Green published the first, I'll say modern, paper on language switching. The idea was to look at the nature of language switching as it had been seen in the task switching literature which we discussed in the previous section. And the idea was to look at people who had to make a response to an item in German, these were German English bilingual and the idea was that they would alternate so they would have an item in German, an item in German then an item in English, an item in English. And they would ask people to respond, and the question was whether they would slow down when they had to switch from English to German, or vice versa. And the finding was that yes, in fact, a switch led to a cost. There was what's called a switching cost. In 1996 I published a paper in which we looked at the nature of switching. The idea was to have people listen to paragraphs through a set of headphones and then see a word on the screen that was placed in a hole in the paragraph and the hole was a missing word that they didn't hear. And that word that they saw, could either fit the paragraph in terms of meaning or fit the paragraph in terms of language. So, we had four conditions, words that fit the meaning and fit the language. Words that didn't fit the meaning and fit the language and then the same two conditions for words that didn't fit the language. The idea was to build upon what’s called priming. The fact that if a word matches the context it's faster to say it, to read it, to make a decision about it, than if it doesn’t. And we wanted to look at the size of this priming depending on whether it fits the language or didn't fit the language. So if we had a sentence like, the dog is walking down the street. Or, the walk, dog is walking down the apple, right. We could also look at a sentence like the dog is walking down the [FOREIGN]. Or the dog is walking down the [FOREIGN]. Now interestingly, [FOREIGN] in Spanish, and that's probably not the best example, actually means can be used in the sense of a street, so maybe we'd use something like, dog is walking down the [FOREIGN]. And oranges don't really have anything to do with walking in the sense that you would walk on top of them. So we looked at this effect, and what we did is we had one condition in which people had no idea what language was coming, whether it was going to be Spanish or English, whether it was going to match the paragraph or not. And in that condition, we found that for words that did not match the language, right, so for [FOREIGN] and [FOREIGN]. There was no difference. There was no priming effect, but if we then made it very predictable, such that every word matched the language in a paragraph, and in other paragraphs every word did not match the language, then we would see this effect. We would see this cross language priming effect, people being faster for words that fit. This was interesting. It was intriguing because it suggests that it had something to do with the fact that we were mixing languages. That this was somehow bypassing the meaning and that people just read the form. In 1999 Meuter and Allport published a paper looking at switching. Again, with the behavioral paradigm in which they used digits between one and nine. And they had bilinguals name each digit in a language, depending on the color of the fonts. So if it was yellow, it'd be one language. If it was blue, it was another language. And the idea was that they would either have to name every digit, so they would get yellow digits one after the other, and they would name those in one language, or they would get all blue digits, and name those in the other language, or they would get a mix, some yellow, some blue. And, when it was yellow, it was named in one language. When it was blue, it was named in another language. And, of course, in that condition, people were slower. The finding that there was this language switching slowdown suggests that switching is switching. That switching between languages is like switching between tasks. It's like switching between looking at the front when you're driving and looking in your mirror when you're driving to see the back. And if this was true, we would expect that it somehow would be related to frontal lobe activity. That this type of switching would have a relationship, or a connection, to the type of frontal lobe activity that we've seen and talked about in the non-verbal switching literature and in the monolingual switching literature. So, shortly thereafter, we ran a study in which we looked at what's called a cued picture naming task. In this task people hear a cue and they see a picture. And like Meuter and Allport instead of the color we'd have a cue. Right. The word say the word Diego. We would have either a mixed condition in which the cue changes on every picture. >> Say. Or a blocked condition in which the cue stayed the same for every picture. >> Say. Now remember, every picture people know exactly what language they're supposed to name in. It's just whether it's alternating, or whether it stays the same from picture to picture. We then went on and tested several groups of people. In a first study, Katherine Connor looked at children, from five, all the way up to adolescence, up until early adulthood. And what she found was that essentially, there was an increase in speed, in terms of producing pictures from childhood to adult hood. Roughly a linear increase in speed. Right. People got faster as they got older. Now, the interesting part was if we looked at the mixed condition. Right? The condition where they had to switch. It was always slower than the blocked condition. People were always slower when they had to switch between languages than when they had to produce an item in the same language across a set of items. But the difference in this cost became smaller across age, and it got the smallest in early adulthood. In follow up studies, we also looked at the effects of aging. What would happen as people became older adults? As they got into their 60s, would this switching effect get larger again? And in fact we did find that, much like the monolingual literature showed afterwards. In our bilingual study we found that this switching effect got larger as people grew older. In fact, in our very first study, our very first subject, we had two different switching conditions. One in which people got a pattern, so they switched on every picture and one in which they had no idea when they were going to have to switch, so they would have a say, a say and then a deega, a deega, a deega, a say, deega, so they had no idea versus a say, deega, say, deega, say, deega. These are actually someone who suggested that it be harder if you didn't know when going have to switch. Well, when Cathy came back with the data she found that the block condition was just fine. In English and Spanish. This unpredictable switch condition was just fine. But when they have to switch to every other picture, so say, deega,say, deega, say, deega. The older adults, this condition had really had a problem. And in this particular subject which we did not use in our data set, they, about halfway through, he or she just gave up and said, I'm just going to do it in Spanish. It's too much work to have to switch on every picture. So this suggests that the switching part is hard. It's not the unpredictability, it's having to switch. These results suggests that language switching has some connection to the frontal lobe, and to the integrity of the frontal lobes. When the frontal lobes are not up and running as efficiently in childhood. There is a larger switching effect, a larger slow down when people are switching. It gets smaller in young adulthood and then it gets larger in older adulthood as the frontal lobe starts to degrade and don't function quite as efficiently. So again, this suggests that there's a connection between frontal lobe function and language switching. But what we really wanted to know was, was there a language switch and where would we get brain activity when people had to switch between languages. So we went in search of the language switch.
