Cool and illuminating blog post.
Read the whole article.Unconscious perceptual processes
This article was inspired by a lecture given by Pamela Smith at the Radboud University Nijmegen.
The purpose of perception is to support behaviour.
Why do we perceive things in the first place? What is the point of it? Is it so we can understand the world? That sounds logical, but that cannot be the whole story. For example a frog can taste, smell and see, but hardly understands. If you look at “lower level” animals you see the direct connection of perception and behaviour.
Frogs have two perceptual systems, one is for finding small objects (=get it and eat it) and the other one is for avoiding large objects (hop away and hide). Thus (at least in frogs) behaviour always follows perception.
But we humans are pretty elaborate creatures (at least we like to see ourselves that way). Do we also have that direct perception-behaviour link? When we see a cup, we do not necessarily have to grasp for it.
What makes us different?
There are two theories of why humans do not react directly to perception (at all times). One of them is called the facilitator-hypothesis and it states that there needs to be another source of energy (facilitator) in order (for the individual) to become active.However another hypothesis has received much more experimental attention and results: The inhibition-hypothesis:
Perceptions always elicits action, but action can be inhibited (Gilbert, 1989).
The inhibition option makes sense, because important parts of the brain are the same as in reptiles. However we have some new structures as well. The neocortical area is sort of built on top of older parts of the brain, so it would make sense that it “adds” a function to the basic brain functions. Another important source of information are patients with prefrontal cortex damage. They often have problems controlling their actions and (re)act impulsively. It would seem that their “inhibition” system has somehow become damaged.Experimental proof for the inhibition hypothesis
Seeing-Grasping
Tucker and Ellis (1998) looked at how we perceive objects. Participants had to say whether objects show where right up or upside down. All objects had handles either pointing to the right or the left. They found an interaction effect between handle side and object orientation. For example when the participants saw a teapot pointing to the right they were faster pushing the right key, even when object orientation was irrelevant to the task. The results of this experiment is usually interpreted as proof for the existence of automatic tendencies to interaction with the object. (If you find that interesting read some studies about embodied, embedded cognitions.)But this is not the only experiment supporting the inhibition hypothesis. There is a brain circuit that is connected to a grasping motion (Chao and Martion 2000). Chao and Martion showed participants different tools. Objects that could be grasped elicited activated that specific brain circuit, even though grasping was not a relevant feature of the task.
Seeing - Taste
Simmons et al. (2005) showed that looking at food pictures activates taste perception. In a study by Zwaan and Taylor (2006), participants turned a button either clockwise or counter-clockwise to indicate whether a sentence makes sense or not. Some of the sentences proposed a clockwise or counter-clockwise motion. Those sentences that implied a certain motion facilitated turning the button in this direction. Again it is important to notice that turning the button was irrelevant to the task.Chameleon Effect
What about if you see somebody performing a certain behaviour? Are you more likely to perform the same behaviour? Yes: It is called imitation and it makes other people like you. It is what Cartrand & Bargh (1999) call he Chameleon effect. A participant described different pictures together with a confederate. In one condition the confederate did rub their face and shook their feet. Participants did rub the faces and shook their feet more if the confederate did so. The best explanation of why they did so seems to be that through imitation they can build rapport with the other person.Couples’ facial expressions
Another example is the imitation of emotional expressions. From a functional point of view this might help understand emotion (Zajonc et al. 1987). Zajonc looked at romantic partners. If you spend a lot of time with a certain person you naturally mimic that person a lot. If that happens for decade you develop the same sort of wrinkles, because you are making the same sort of facial expressions every day, again and again. Observers rated husband and wife as looking much more similar than random paired strangers.Priming “elderly” reduces walking speed
Reading about old people makes you walk to the elevator much slower (Bargh, Chen, & Burruws, 1996). In their experiment the task was to make sentences with words that included words that primed participants with the concept of elderly. Thought the spreading of activation with activate the concept of elderly, which in turn activates the concept of elderly. This actually influences walking speed on the way back to the elevator (dependent measurement).Smell of cleaning fluid makes you behave in a clean way
Rob Holland could show that the same effect can be shown using smell as the activator of a concept (Holland et al. 2005). People filled out an questionnaire in one room. Some participants sat in a room where there was a bucket of water with a little bit of cleaning fluid. Then all participants went into a room free of smells. They then had to eat a biscuit that crumbles a lot (very messy). Participants were recorded on video and observers counted how many times participants picked up the crumbs/cleaned the table. People who first sat in the room with the smell of cleaning fluid did pick up the crumbs significantly more often. Thus we see the concept of perception and action coming back once again. Presumably the smell of the cleaning fluid activated the concept of “clean”, which then became connected to action while eating the biscuit.Conscious or unconscious?
Owen at al. (2006) put patients that were in a vegetative state in the FMRI and they were given instructions to visit different situations, such as playing tennis or visiting the rooms in their home. You can clearly see that the brain activity in the patient and the control show pretty much the same activation pattern. So the patient was able to understand the instructions and act upon it. However was the patient really conscious or could the effect also be explained by unconscious processes?
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