The human perceptual system is able to enforce a large array of illusions on our conscious experience. Most importantly, we hold the illusion of a complete and vivid picture of our surroundings, while in fact we selectively ignore nearly everything we see.
There’s a good reason for this, of course: focusing on the task at hand generally consumes nearly all of the processing power our brains have to offer. If we need to shift our focus to another aspect of our surroundings, we can do it nearly instantaneously. But how do we decide which items to pay attention to? There are a couple possibilities. We might pay attention to the kind of things we’ve seen or heard about recently (priming). But the process might be more conscious: we pay attention to the kind of things we intend to do something about. For example, if I’m driving a car, I might notice red things more often than other colors, since I’m on the lookout for red traffic signals indicating that I need to stop.
So how do you find out if priming or intention is a more important factor in what we pay attention to? The first thing is to create a task that maxes out your multi-tasking ability. Take a look at this video (QuickTime required). You’ll see one word flash while you hear another word. Your job is to ignore the audio words, snap your left hand if the printed word is pleasant, snap your right hand if the printed word is unpleasant, and knock on the table if the printed word is an animal. The audio words are just there to make the task more difficult; focus on the printed words:
A team led by Richard Marsh asked 103 college students to complete a similar task, but it went on for much longer: there were 100 trials, with just four animals over the course of the entire task. Pleasantness was rated on the using a scale on the computer, and the student volunteers had to press the slash key whenever an animal name appeared.
After this initial task was completed, there was a surprise test on the audio portion of the task. 32 words were presented, and the students had to indicate whether they had heard those words previously, or if they were new words. Four of those words were animal names that had, in fact, been played previously. Four were plant names they had heard before, four were other unrelated words that they had heard before, and the rest were distractors. So how accurate were they in remembering those words?
When the students were looking for animals in the printed words, they remembered more of the animal words they heard compared to plant words they had heard (A separate group of students was asked to look for plant names, with the equivalent result). It appears that we remember more of things in the background when they are related to what we intend to do. In another experiment, the same result wasfound when asking students to look for breakfast foods.
But how do we know if this effect is actually due to intention, and not just the result of priming? In a new experiment, students were told that they’d be looking for animals, but only during a future test where they would be counting syllables in a word. In the first task, otherwise identical to the original experiment, the students rated pleasantness only, without looking for animal words. Then they were never given the syllable-counting task, and instead went directly to the memory test. Here are the results:
This time, there was no significant difference, even though the students had been told they would be looking for animal names in a future task. When searching for animals wasn’t required during the actual task they performed, they didn’t remember more animal names. Marsh’s team argues that the effect they observed in their first experiment could not be due to priming, and instead must be related to the observers’ intentions.
So, in this scenario at least, it appears that our intentions guide our perception of the world around us. We notice, and recall, more items that are related to our immediate goals, and we ignore, and forget, other items.
Marsh, R.L., Cook, G.I., Meeks, J.T., Clark-Foos, A., Hicks, J.L. (2007). Memory for intention-related material presented in a to-be-ignored channel. Memory & Cognition, 35(6), 1197-1204.