Sandy: Hey Pat, are you coming back from lab? How was it?

Pat: Hey Sandy, what’s up? Yeah, back from lab. We did vision again tonight, another weird experiment.

S: What was it this time? Stand on your head and recite your childhood memories?

P: No, it was worse than that. We used mirrors to split our brains into two parts that didn’t get along. My head still aches.

S: Oh, binocular rivalry!

P: You know about that?

S: Sure. My friends and I used to sneak out behind the High School with little mirrors. We used to call it "splitting." Like, "Oh, man, am I split!"

P: Wow. You’ve done a lot with altered states of perception, haven’t you?

S: Yeah. As Timothy Leary says, "Why not?"

P: I’m surprised you’re not in this lab then. Perception is all we talk about.

S: Oh, you do baby stuff. Early processing. Boring.

P: What do you mean?

S: Well, let me put it to you this way. When you walk into that classroom, do you look around for E’s and F’s? Do you check the rotating cylinders, or people doing jumping jacks?

P: No... but my perception is a more complex version of looking for those sorts of things. We examine simple cases of more complex stuff. They’re like components of a stereo system. Each is simple, but working together they add up to real human vision.

S: Maybe, maybe, but look, what do you look for when you walk in there? What makes your heart go wild and your palms sweat?

P: You know the answer to that. It’s Chris.

S: Yes, Chris. Every week I hear about you and Chris. Do you sit close to each other, get to work together, whatever. It’s all you talk about.

P. Well, I’m obsessed with the relationship -- if you could call it that. I don’t even know if Chris knows I exist!

S: Now, there’s vision in action, real human vision. Everything you do in that classroom passes through a "Chris filter."

P: A "Chris filter"?

S: Yeah, you have Chris on the brain, man. Your Chris obsession drives what you look for and what information you extract from the visual world. It determines your actions, too. I’ll bet you sit in the room in order to have a clear Chris view.

P: Of course. It’s really distracting, too. We’re supposed to be doing something, but it just falls out of my head. I’m supposed to be recording my observations, but all I can think is "Chris, notice me!"

S: I hear you. It’s human nature. We try to keep on a task, hold it in mind, but we get dragged away by distractions. For you it’s Chris, for me it’s my beeper. The mind is always being pulled apart.

P: Exactly. Dr. Dan’ll say something like "Raise your hand everytime I use the word 'perception.’" So it’s like I put that instruction on my "do list." I’ll be paying attention to what he’s saying, trying to remember to do what I’m supposed to do, but then I get distracted.

S: Now that’s real life. Your lab would be really cool if you could look at that. How does that "working memory" thing work? Under what conditions does it get bumped out by a distraction --

P:--like Chris--

S: --like Chris. Now if your lab looked at that, I’d be there!

Sandy should stop by. Tonight we consider working memory, the capacity to hang onto crucial bits of information for short periods of time. The information can be perceptual, like items in a room, or linguistic, like items on a list, or it can be tasks to do, as in Pat’s example. Working memory, also known as Short Term Memory, has a limited capacity, as we will experience in the introduction to the lab. It is also subject to interference effects, of which Pat’s romantic obsession may be an extreme case. Interference will be the subject of tonight’s exploration.

By now we have seen several lines of evidence that suggest that the visual world is not simply recorded by passive eyes and passive minds. Instead, the active mind actually creates a great deal of what is seen. Much of the mind’s creative activity is automatic; the world pushes the buttons and the mind responds by leaping to a conclusion. For example, consider the two labs in which we observed features that "pop out" at us: preattentive features and solid forms made of moving dots. But much of the mind’s creative activity is deliberate. By attention, we can control not only what we look for, but what we can see. The Cheshire Cat lab showed how dramatically attention can alter what is seen in a special circumstance of binocular rivalry. It also showed that deliberate heedful attention is in a tension with distraction, with things that "call attention to themselves."

Tonight we explore other manifestations of this tension between heeding and distraction, and between deliberate action and automated response. The lab involves taking the Williams Inhibition test, a simple test where you match circles by size. Size is the only relevant property in the matching task. However, inside the circles are distracting stimuli, like letters and numbers, which do not correspond to size. You must ignore the distractors and keep on sorting by size. You’ll find this difficult to do, however. The difficulty will be detectable in two ways: Your reaction time will increase in distracting circumstances; and you’ll make errors when the distractions are present. The question to explore is, what features of the distractors interfere most with the task? And: Why?

This is best done with a partner.

This lab uses a software package known as the "Williams Inhibition Test." As you arrive in the lab, look on the desktop screen to see if the TAs have already copied the "Williams Inhibition Test" folder onto the desktop. If it is there, jump to step 3. Otherwise, follow all these steps.

1.The path:

Mac HD

Network Servers

Class software

2. Click on the folder Williams Inhibition Test.

It will take a minute to copy.

3. Open the "Williams Inhibition Test" folder.

4. Click on the icon labelled "WIT -- Williams Inhibition Test."

1. The test is a hypercard stack. To begin, read the opening screen.

Your mouse should be in good order to take the test.

2. Take turns: First your partner will take the test, plot the results, and print them. Then it will be your turn.

3. When you are ready, click on the arrow pointing to the right and take the test.

4. As you finish, you’ll see a screen labelled: "Williams Inhibition Test (WIT) Scoring."

Click on: Plot Results. This screen is shown on the last page of this handout.

5. You’ll see a graph that plots your response time (light line) and cumulative errors (heavy line). Print this graph by hitting Command-P. (The apple key and the letter P.)

6. When you have the printed graph, click on the arrow at the top left corner of the graph screen. You’ll return to the Scoring screen. Click on Restart. The second partner now takes the test. If you have your graph, you should not need to save your data.

This program is rather crude, and allows only limited interaction. This limits the possibilities for new experiments. But with everyone doing the same experiment, it will be possible to compare notes more exactly. See if you can compare notes with other teams. If you are working outside the lab, sit some friends down and make them take the test too.

In your report, please address the following questions:

3. Describe a NEW experiment that might be conducted to further test your hypothesis. Note that we won’t be able to conduct this experiment. Explain what the outcomes of this experiment would reveal.

You may hand this in as hard copy or via Docex, in the "Phil 371" drop or sharing folder. Make sure both names are on the report, and please put your names or initials in the filename too. Try to finish tonight, but if that is not feasible, reports will be accepted until 4 PM tomorrow. (Please bring them to my office, McCook 325.)

For Docex drops, do not use MacWrite Pro. Use WordPerfect instead.