6.8 Anne Treisman & Feature Integration Theory
Two Types of Attention
You are in a crowded shopping mall and you are searching for your friend. You know she can’t be far. She has brown hair and glasses, but many other people have brown hair or glasses. Finally you remember that she is wearing a hot pink jacket. Voila – there she is. It’s as if that hot pink jacket has just popped right out from the crowd.
In this example, you just witnessed two types of attention at work. The first type of attention required you to search more carefully, person by person. The second type of attention allowed you to scan the crowd all at once, requiring no effort at all. What you were looking for the second time (the hot pink jacket) popped right out at you.
Let’s take a look at another example. In each of the two boxes below, look for the letter R among the P and Q distractors.
What did you notice? Was the R a bit easier to find in the box on the left than in the box on the right? You may have even had to search within the box on the right for a few seconds in order to find the R. This is because the box on the right has more distractors (more P’s and Q’s). This is kind of like searching for your friend’s brown hair and glasses in the mall. When there are only a few other people, it is easy to find your friend. However, the more additional people there are, the longer it takes to locate your friend.
Okay, let’s try one more example. Now, see if you can find the L among the O distractors in each of the two boxes below.
This time the search was a bit easier, wasn’t it? It’s as though the L just pops right out of all of the O’s. In fact, it probably didn’t take you much more time to find the L in the box on the right than the box on the left. Even though the box on the right has more distractors in it, the amount of time it takes to search for the O in either box is about the same. This is like searching for your friend’s hot pink jacket in the crowded mall. It really shouldn’t matter how many other people are in the mall so long as your friend is one of the only ones wearing a hot pink jacket. Why is that?
Feature Integration Theory
Remember how, at the beginning, I mentioned that there are two different types of attention at work? That is exactly what researcher Anne Treisman has proposed is going on when we search for anything in our environment. In her feature integration theory, she explains that we use a more automatic type of attention when we are searching for a single feature, like the hot pink color of your friend’s jacket. However, when we need to search for a combination of features, like both your friend’s glasses and her brown hair, a different type of attention is needed, which is more deliberate and slow.
In the boxes above with the L’s and the O’s, the target (the L) can be distinguished from the distractors (the O’s) by searching for a straight line since the O’s don’t have any straight lines. According to feature integration theory, in displays like these where a single feature can be used to search for a target among a set of distractors, a parallel search takes place. This means that all of the items can be searched at the same time. Because all of the items can be searched at the same time, increasing the number of distractors does not increase the amount of time that it takes to find the target. The target just seems to pop out regardless of the number of distractors.
In the boxes above with the R’s, P’s, and Q’s, the target (the R) can’t easily be distinguished from the distractors (the P’s and Q’s) because there isn’t a single feature that distinguishes the target from the distractors. The P’s share the straight line and rounded top with the R, and the Q’s share the angled line that protrudes from the lower right-hand side. In order to find the R, you have to look for a combination of features since searching for any one feature alone won’t work. According to feature integration theory, a sequential search is needed when a combination of features distinguishes a target from distractors. A sequential search means that items are searched one by one until the target is found. Because of this, unlike the parallel search, a sequential search takes more time as the number of distractors increase.
Attention as a Spotlight
Okay, back to attention. Attention can be thought of as a spotlight. Whatever falls within that spotlight, we pay attention to. However, the size of the spotlight can change. When you engage in a sequential search to find your friend in the mall, which requires you to look from person to person until you find her, your attention spotlight becomes much more narrow and focused. This is referred to as focused attention because, well, you have to focus your attention on individual people. However, if you switch to a parallel search based on your friend’s hot pink jacket, your attention spotlight becomes much larger and less focused because you can scan the whole crowd at once. This is referred to as distributed attention because your attention is distributed among many people.
According to Anne Treisman’s feature integration theory, when we search for a target among a bunch of distractors, it sure helps if that target has a unique feature that isn’t shared with the distractors. When the target has a unique feature, we can use a wide spotlight of distributed attention to engage in a parallel search. This allows the target to simply pop out and means that our search will take hardly any time at all – even if there are a lot of distractors. However, if the target does share features with the distractors, then we need to look for a combination of features to find the target. That means we need to narrow our spotlight of attention, making it more focused, so that we can engage in a sequential search. A sequential search makes it so that the more distractors there are, the longer it will take us to find the target.