Hack79.Make Events Understandable as Cause and Effect | Mind Hacks. Tips and Tools for Using Your Brain

Hack 79. Make Events Understandable as Cause and Effect

By following a couple of simple rules, you can show a clear pattern of cause and effect, and ensure your viewer is able to make the connection between separate things happening at the same time.

Research suggests that just as the visual system works to recover the physical structure of the world by inferring properties such as 3-D shape, so too does it work to recover the causal and social structure of the world by inferring properties such as causality and animacy.¹

Perception is finding structure in sensations. Finding a structure to things lets you hold them in mind and store them in a memory-efficient way. If the structure corresponds to reality, it can also be used to provide predictions about the thing you're representing. So it's easier to think of several sections of cable on your desk as all being part of the same mouse lead, and once you've assumed that it's easy to find the mouse, you just follow the cable away from the stack.

We've already seen that the brain looks for structure in space [Hack #75] and structure in time [Hack #76] to organize perceptions. These principles apply to the basic perception of physical objects, as well as helping us understand how we make sense of our body images [Hack #64] and the bodies of other people [Hack #77] .

But our visual system doesn't look for just static physical structuresit can also pick up on causal relationships between things. You don't see two things happening but rather one event: you don't stop to wonder why the plate smashed just at the same moment that it hit the floor.

This ability to detect causation and animacy [Hack #78] is a perceptual phenomenon, different from our slow deliberate reasoning about what causes what ("Hmm...why does my computer crash only after I have written at least 2000 words without saving?" is a different kind of nonperceptual, causal reasoning).

When our visual perception picks up on causes it does so quickly and without any conscious effort on our part. Like with many visual illusions, it happens without your consent and without any ability on your part to stop it, even if you wanted to and know that it is illusion.

8.6.1. In Action

Here's one way of seeing what I mean when I talk about the perception of causation. Make a pendulum, using whatever you have lying around and find something of similar size to whatever you use as a weight. It doesn't really matter what you use; I am using the cord from my camera with my keys as the weight. You'll also need another small object; I'm using a large red bottle lid from a drink bottle.

Hold the pendulum up in front of you and set it swinging left to right. Now take the other object in your free hand and wave it around at the side of the pendulum. It doesn't feel like anything special, does it? Now move the other object (in my case the bottle cap) in time with the pendulum, trying to keep it a fixed distance, say 5 inches, from the swinging weight. If you get the timing right, you should get the unmistakable impression that the object in your free hand is pulling the pendulum weight along and then pushing it back. This happens even though your body has direct evidence that the two events are causally unrelated: the pendulum moves itself and your own hand moves the unconnected object.

Notice that you don't just see the two things as moving together. You get a feeling, manufactured by your perceptual system and delivered direct into consciousness, that one thing causes another.

8.6.2. How It Works

The rules that govern the perception of causation are those you might expect. Events that happen in close succession and those that have a consistent relationship appear to be causally connected. But how close together in time and how consistent do things have to be to be perceived together?

One way of studying these questions is something called the launching paradigm (http://www.carleton.ca/~warrent/210/michotte/michotte.html), which was developed by Albert Michotte.

In the first demonstration (http://www.carleton.ca/~warrent/210/michotte/michotte1.htm; animated GIF), a red ball enters at the left of the screen and moves until it meets another red ball in the center of the screen. The first ball then stops, and the second ball moves off to the right. What you actually see however is more than that; you see a ball come along and knock into another one to start it moving, as in a game of pool.

If there is a pause between the two events, as in the second Michotte demonstration (http://www.carleton.ca/~warrent/210/michotte/michotte2.htm), you don't get the same impression of causality. How big does the pause have to be? Research has shown that if the pause is longer than 140 milliseconds, the feeling of one event causing the other is removed.²

I think this figure of 140 milliseconds might explain why, at a certain delay, using a gadget becomes annoying. If you press a key on your keyboard but the letter doesn't appear until a quarter of a second later, it removes the feeling that what you are doing with the computer is happening at the same time on the screen. The device stops being invisible in use and that stops you using it without thinking. It's annoying, in other words. I stop being able to type and have to start pressing the keys individually and waiting for the letters to appear on the screen before I press another one.

T.S.

Spatial separation can also affect the perception of causality, although this isn't as critical as timing, as the pendulum test shows. A gap between the two balls in the launching paradigm removes causality, but this is a one-off causal relationship rather than a continuous one as simulated in the pendulum example. You can restore the feeling of causation by adding another ball between the two separated balls, so that you get a chain reaction from the first ball to launch the final one. Although the first and last balls are doing exactly the same thing as in the simple spatial separation example, making visible a causal relationship between restores the feeling of causality. Brian Scholl's movie at the Yale Perception and Cognition Laboratory³ illustrates this (http://research.yale.edu/perception/causality/toolEffect.mov; QuickTime).

Scholl has also shown that visual events that don't normally create feelings of causal connection can be changed by the addition of other, related, simultaneous events that do create a perception of causality. This shows again that timing is the most important factor our visual system uses for inferring causality. (Incidentally, the reverse relationship also appears to be true. Events that we code as being causally related we perceive as being closer together in time than we would otherwise.⁴)

So whether we perceive two events as causally connected is affected by what else is going on. When you hit a nail with a hammer, you feel as though you're the cause of the nail going in, even though your intention (the cause) and the strike (the effect) are separated in both time and space. The hammer, as a tool that provides a visual connection between the start and end events, ensures that a feeling of causality is presentone that wouldn't be if we saw the cause and effect events without it there.

Experiments have shown that delays of more than 2 seconds can prevent people learning that one event causes another⁵although subsequent work has shown that something as simple as giving people a reason for the delay can double the maximum length of the cause-effect gap that can be coped with.⁶

The important message is that the brain doesn't really believe in coincidence, so if you can show what looks like it should be a causal effect, the brain will manufacture up a feeling of causation to go along with it. You can overcome a lack of direct contact between events by changing context, but you must get the timing right.

8.6.3. End Notes

Scholl, B. J., & Tremoulet, P. (2000). Perceptual causality and animacy. Trends in Cognitive Sciences, 4(8), 299-309.
Michotte, A. E. (1963). The Perception of Causality (T. R. Miles, trans.). London: Methuen & Co.
"Basic Causality & Animacy Demos" from Brian Scholl's pages at the Yale Perception and Cognition Laboratory (http://pantheon.yale.edu/~bs265/demos/causality.html).
Eagleman, D. M., & Holcombe, A. O. (2002). Causality and the perception of time. Trends in Cognitive Sciences. 6(8), 323-325
Shanks, D. R., Pearson, S. M., & Dickinson, A. (1989). Temporal contiguity and the judgment of causality by human subjects. Quarterly Journal of Experimental Psychology, 41B, 139-159.
Buehner, M. J., & May, J. (2004). Abolishing the effect of reinforcement delay on human causal learning. Quarterly Journal of Experimental Psychology, 57B (2), 179-191.

8.6.4. See Also

You have to pay attention to events to get the perceptual impression of causality: Choi, H., & Scholl, B. J. (in press). Effects of grouping and attention on the perception of causality. Perception & Psychophysics.