Saturday, June 23, 2012

Automaticity, the Stroop, and Human Behavior

Think back to when you learned to tie your shoelaces; you needed to think carefully through each step of the process. Probably, you made errors over the course of multiple attempts. Now you probably do not even think about the steps, but simply initiate a series of movements that proceed without any further influence. There are many behaviors that followed this same pattern of learning: reading, writing, typing, bicycling, piano playing, driving, etc. When a behavior no longer requires direct, deliberate thinking to perform, the behavior is automatized.

The amazing thing about automatized behaviors is that many people state that they do not consciously know how the behavior is performed, they just can do it. This is typically referred to as unconscious memory or implicit memory. For example, try explaining how to properly maintain your balance while riding a bike. Difficult, right?

In some instances, a behavior can be so over learned that we do it automatically. Or, in other words, we do it without thinking. A great example of this is reading. For literate people, it's impossible to not read. What I mean by that is, if a random word were to flash on the screen, you could not stop your self from reading it. Even if the word were flashed on the screen for a fraction of  second so that it only appeared as a blip, you would have a better than chance probability of identifying the correct word if it were presented again alongside another random word.

Not only can behaviors become automatized, some behaviors can be more automatized than others. And when you have automatized behaviors compete against each other, you get interference, or the slowing down of a behavior. This concept was best and most famously demonstrated in what is known as the Stroop effect named at J.R. Stroop.  In Stroop's classic experiment, participants were slower to properly identify the ink color when the ink was used to produce color names different from the color of the ink. That is, participants were slower to identify red ink when it spelled the blue. What makes this finding interesting is that participants are specifically instructed not to pay attention to the word names and simply report the color of the ink. However, this seems to be a nearly impossible task, as the word name seems to interfere with the participant's ability to report only the ink color.

Below is an example of the Stroop task. First read the color-matched words (trial 1) and then name the colors of the X's (trial 2) as quickly as you can. Note how quickly you're able to complete each task. For the third trial, try NOT read the word, but rather name the ink color in which the word is printed.

The difficulty you experience completing the third trial relative to the other two is interference. The automaticity of reading is eliciting a response that is different from the one that is required (naming the ink color) and therefore competes with the response that your suppose to make.

Aside from this being a cool demonstration of automaticity, did you know that you can use automatic behaviors to influences the behavior of others? In an experiment done by Langer and colleagues, it was demonstrated how compliant people will be with a small request as long as they heard what sounded as if they are being given a sound reason, even though no actual reason is given. In the experiment, an individual approached people standing in line to use a copy machine and presented one of three requests:

1. Excuse me. I have 5 pages. May I use the Xerox machine because I am in a rush? (sound reason)
2. Excuse me. I have 5 pages. May I use the Xerox machine? (no reason)
3. Excuse me. I have 5 pages. May I use the Xerox machine because I need to make some copies? (non-sound reason).

When given a request plus a sound reason (#1), 94% of subjects complied with the request. However, when given a request with no reason (#2), only 60% of subjects complied. But when given a request plus what sounds like a reason (#3), but actually wasn't a reason, the compliance rate jumped back to 93%!

What people were responding to was not sound reasoning, but to syntactical structure: a request followed by what should be a sound reason. Most of our behavior, it turns out, is automatic. That includes speaking and thinking. In other words, when we are doing something, we are doing it without occupying our minds. This means that our minds are often free to engage in other, higher order, and more meaningful activities; like watching TV.

Wednesday, June 20, 2012

Saccadic Masking, Chronostasis, and Concsiousness

Time. What is it? To some, Time is a kid-friendly news magazine characterized by info-graphics and colorful pictures. To others, Time represents a continuum of continued progress of events from the past, present, and future. While Time is indefinitely continuous, its rate can appear quite variable, at least to humans.

Below is a clock face with an active seconds hand. Focus your gaze on something nearby (e.g., something just above your CPU monitor) then shift your gaze to the clock and watch time elapse for 5 seconds. What you should notice is that the first second to elapse appears to take longer than the subsequent 4 seconds (It's subtle, you may have to try this a few times to notice the illusion).
If you did notice time lag, then you just experienced chronostasis. Chronostasis is the experience or illusion that occurs immediately after a saccade that appears to stop time momentarily. This occurs so much that every day we experience 40 minutes of chronostasis, though it goes entirely unnoticed.

So what's going here? When our eyes move, the image reflected on to the retina is also in motion. This creates 
motion blur (see picture at beginning of this post). A blurred image being utterly incomprehensible (and of no use) to us sighted humans, our brains have a mechanism to circumvent the blur an create a comprehensible image. This phenomenon is known as saccadic masking. During saccadic masking, the blur is suppressed, along with visual processing, and the gap in visual processing that should be experienced as your eyes move from on side to another. The brain then replaces the blur with an image of the very next thing that your eyes fixate on.  

This explains chronostasis experienced in the clock illusion. As you shift your gaze to fixate on the clock, instead of seeing a incomprehensible blur, the blur is supplanted with an image of the clock that your currently fixated. That's why that first second to elapse appears longer than all other subsequent seconds.

The process is depicted below:

The first figure depicts what actually occurs, but only our subconscious brain perceives. Figure two shows what what we actually see. If you imagine that point two is the image of the clock, our brain then fills in the time that had motion blur with the same image. 

If the brain is replacing a past image with a current image, does that mean what I'm seeing is not really in the present but the past? Yes, in fact, human awareness or what we experience as the "present" is actually the very recent past; more specifically our consciousness lags 80 milliseconds behind actual events. This is how saccadic masking and chronostasis are possible; before we become aware, our brain has to make sense of stimuli first, which takes just about 80 milliseconds.

As it turns out, saccadic masking and the 80 millisecond lag in awareness explain many of the visual illusions that many may already be aware of such as the moving snake illusion. As you move your eyes looking at the image below, the illusion of motion is apparent. If you fix your gaze on a black dot, the illusion of motion will cease. 
There are other phenomenon as it relates to time perception: Time passing more quickly as we age and time slowing down as we become scared. Of course, the latter phenomenon should not be confused with time dilation, which is an actual difference of elapsed time (as opposed to perceived difference) between two events as measured by observers moving relative to each other.