Thursday, November 12, 2009

Psychology took me to Salt Lake City, and it followed me there.

One of the coolest things about choosing to study psychology is that it’s more than likely that you will see the phenomena your lecturers talk about actually happen in real life! After all, psychology is the study of human behaviour and cognition, so by definition you should experience your own and others’ behaviour and cognitions every day.

After taking a course in social psychology you’ll be acutely aware of group dynamics such as social loafing and conformity. It’s also easy to observe concepts from developmental psychology in real life, like the language development of little brothers and sisters, or nieces and nephews.

Not all areas of psychology, however, are as obvious in real life as the examples above. I am interested in concepts like perception and attention, which are often studied in highly-controlled experiments. Typically, these experiments involve a first-year student being roped into sitting in front of a computer for an hour to press buttons in response to stimuli. It’s not very likely that you will encounter this set-up in your day-to-day life, making it equally unlikely you’ll experience these perceptual phenomena outside of the lab or away from a computer.

For that reason, it’s very exciting to experience a visual phenomena usually restricted to computer monitors and dimly lit rooms, and even more exciting being able explain it with psychological theory! This is what happened to me on a recent conference trip to the States.

Being my first visit to the USA I managed to take a few weeks out from the conference to visit academic friends in various parts of the country, including a former lab colleague who now resides in Salt Lake City, Utah. We took a day out to hike up to beautiful Lake Blanche in the Wasatch National Forest.

This hike was always going to be a challenge for me. Having average (at best) fitness, and coming from Brisbane, which is warm, humid and close to sea level (the highest point in Brisbane is 287m above sea level - Mt Cootha). The hike we planned was a 6km trek (12km round trip) and included an 850m ascent to 2750m above sea level.

We took it easy and reached Lake Blanche after 3-4 hours of hiking, drinking litres of water on the way up. After having lunch and admiring the scenery I started to feel the effects of altitude sickness and/or dehydration (yes, dehydration, water vapour is lost from the lungs at a higher rate at these sorts of altitudes). This included light-headedness, nausea, and a headache.

Aware that light-headedness compromised my concentration, and that this may be dangerous for the descent, I tried to remain as focused as possible on the ground in front of me and where I needed to place my feet. This became fairly automatic after a while. With my eyes locked onto the obstacles moving towards me, I would go through the process of identifying potential hazards, placing my foot in a safe position, bending my knees to reduce impact damage, and then identifying the next hazard.

I kept this up for half an hour, eyes locked onto the pattern of rocks constantly moving towards me. It was then my hiking partner pointed out to the mountain running parallel to ours, exclaiming at how far we'd descended.

I peeled my eyes from the ground and redirected them towards the mountain in the distance. What I saw completely surprised and shocked me. The mountain was moving! To me it seemed like it was growing out of the ground and tapering off at the top. I decided this was a hallucination related to altitude sickness/intense dehydration.


It was as I was sitting down that I had my Eureka moment. The hallucination had really taken me by surprise, I didn’t think my condition was that bad. Then I remembered how I’d kept my eyes locked onto the ground for so long. The constant visual flow of the ground moving in one direction replicated part of an illusion known as the Waterfall Illusion. The Waterfall Illusion demonstrates a widely replicated perceptual phenomena known as a motion aftereffect, where, after viewing a constant moving stimulus, a stationary stimulus appears to move in the opposite direction to that which had been moving. For more information on motion aftereffects the wiki page is quite useful:

This is exactly what I think was happening with the mountain growing out of the ground. When my eyes were locked on the ground there was a constant moving stimulus coming towards me, or (as expected when looking directly down at the ground) moving from the top of my visual field to the bottom. When I looked at the stationary mountain it appeared to move in the opposite direction to the moving stimulus, that is, moving from the bottom of my visual field to the top.

How cool is that?!?

Thanks to our good friend Dave Liu for taking the photo!

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