Thursday, November 26, 2009

Look again!

Over the past couple of weeks, Matt and Morgan have upped the anti with blog posts with pretty pictures. Matt shared some of his visit with a couple of stars of psychology, while Morgan gave us a nice summary of a well established illusion. So, now I have to try a bit harder. For this post, I want to show everyone one of my favourite visual illusions, and give you a quick run down on how it works.

I think the illusion, below, is the most compelling illusion ever, and you probably wouldn’t even believe what the illusion is without the additional pictures (I certainly wouldn’t). Seemingly, it’s just a swirl of pink, green and blue, right? WRONG! Actually, what seems like green and blue, are exactly the same colour!!!

Now, you probably don’t believe me, so in the version below, I edited in an aqua-coloured bar that is the same colour as both swirls and zoomed in.

So why does this happen? Why would our brain tell us so convincingly that two colours are different when they’re not? Have another close look at the purple and orange spirals that seem to run continuously around - the orange lines stop before the “blue” stripes, while the purple lines stop before the “green” looking stripes. Our brains like to fill in visual information, so at first glance we see the purple and orange loops as continuous. Then, without us realising, our brains contrast the darker colour of purple to the aqua, making it seem greener, and then contrast the the lighter colour of orange to the same aqua, making it seem darker. That is a simplified explanation, but, wow, what an illusion.

I saw this illusion posted in an online forum, one poster said in reply to the picture, "If we all get tricked by the illusion, then we are all seeing the same thing." This is an interesting sentiment - if everyone's brains process the image as being two different colours, does it matter that there is only one colour when we look at it closely? Maybe not, but it's still cool.

This illusion was created by an illusion legend, Akiyoshi. Be sure to check out all of his other very impressive colour illusions here: - you might soon find out that your brain is tricking you more often than you realised!

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Wednesday, November 18, 2009

Ramblin' Man

It's said that one of the perks of academic life is travel. I can vouch for this. I'm a first-year PhD student but have already made two trips to the USA without spending a dime.

The purpose of this post is partly to gloat but mostly to convince you to take the opportunity to travel during your PhD and realise the value of getting your name and face out there on the international stage.

In October I was invited to speak at the University of California Irvine and the University of Lethbridge in Canada. (Securing funding is much easier if you can get someone to invite you!) I met Associate Professor Simon Cole, a big player in my research field of fingerprint identification. He gave me some tips on where to focus my research and his grad students showed me where they work and play.

Associate Professor Simon Cole and Matthew B Thompson
Associate Professor Simon Cole and me

I was then treated to dinner by Professor Elizabeth Loftus. I'm sure you'll know her. She is best known for her pioneering work on the misinformation effect and the implications for eyewitness testimony. Loftus sits half way down a list of the 100 most influential researchers in psychology of the 20th century (just below Posner and Broadbent : ).

Professor Elizabeth Loftus, Matthew B. Thompson, Shari Berkowitz
Professor Elizabeth Loftus, Me and her grad-student Shari Berkowitz

I also attended the Annual Meeting of the Human Factors and Ergonomics Society in San Antonio, Texas. An intense week: 8 hours work, 9 hours play, rinse, repeat. The powers that be were impressed by our creation of the first HFES student chapter in the Southern Hemisphere -- HFES-UQ. Because Tobi, our wonderful president, couldn't make it (he made up some excuse) I was treated like an academic rock star by the organisers and fellow students.

Matthew B. Thompson
Morgan, Dave and I receiving an award on behalf of HFES-UQ from Assistant Professor Sandra Garrett

Despite all this nerdy stuff, I still caught a Bruce Springsteen concert in New York with my dad, got drenched at Niagara Falls and cruised down the Las Vegas strip hanging out a limo sunroof drinking beer with my mate Morgan (not on tax-payer's dollars of course).

Matthew B. Thompson
Morgan and I in a limo on the Las Vegas strip

So, get your academic persona out there and be sure to have some fun in the process!

Matthew B. Thompson

I thank HFES-UQ, NICTA and my advisors Dr Jason Tangen and Professor Penelope Sanderson who made this trip possible.

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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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Saturday, November 7, 2009

Working on Weekends: Effort vs Reward

I often come to uni on my weekends to get extra bits of work done. Sitting here in my office on weekends might be kinda sad from a social point of view. Maybe sadder still is that I actually enjoy being at uni at least 6 days a week.

I’m determined this weekend to finish revisions on a manuscript that my collaborators and I are re-submitting on Thursday. This morning when I arrived at my desk, however, I remembered the first year statistics assignments that I still have to mark. Like a lot of other postgrads, I subsidise my scholarship by tutoring statistics classes during semester, which is a heck of a lot of fun… until I have to mark all the assignments instead of working on my own research.

It’s a tough job to work out how to balance how much feedback to give the students versus how much time I spend per assignment. The first two assignments took me an hour each to mark, and now that I’ve gone through about 15, they’re taking me closer to half an hour each. (To put that into some perspective, I roughly get paid for fifteen minutes per assignment, which is extremely unrealistic.)

The amount of feedback I have been giving really comes down to how well the student has done. Really good assignments take very little time to mark, and require very little feedback on my part. Really bad assignments take very little time to mark - I don’t give them much feedback either. Instead, at the bottom of the marking page I write “Come and see me if you would like to discuss your mark”, knowing most students who get the really bad marks won’t read that far down the marking page, if they bother looking at it at all.

I tend to give the students who perform around the middle the most amount of feedback. My guess is a lot of these students have put in as much effort as the top-performing students, but struggle to understand the key concepts. I think these students need to have their errors made very obvious to them, but they also need to be encouraged to keep trying has hard as they did. After all, the research shows that we should reward effort rather than grades.

Unfortunately, when it comes to re-submitting our manuscript next week, the peer-review process cares less about the effort we put in, and more about the scientific clarity of the research as a whole. Worst-case scenario, if the manuscript gets rejected, I hope it’s at least in the mid-range so I’ll get lots of feedback!

Are you studying Psychology@UQ and want to contribute to theuqpsycblog??
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Tuesday, November 3, 2009

A Ride Down Multisensory Integration Lane

This morning I experienced a variation of the ventriloquist effect which I’ll explain soon, but first, a bit of background to the story. I’ve started riding to UQ this year, and I’m so into riding now that I just bought a new, shiny road bike, and go for long rides around the Brisbane River before getting to uni. An advantage of my road bike is that the gears shift very smoothly and easily, which makes it easier to adjust my pedaling to go really fast, or to go up hills. Every time I press the gear levers with my hands, I feel the change of the bike chain move from one cog to another in my feet, which is usually accompanied by a metal “clicking” noise. So, every time I change gears, I feel something in my feet, I hear a “click”, and the feeling and the sound always happen at exactly the same time.

On my ride this morning I got to a part of the bike path next to a road works area and I needed to change gears. I pressed the gear levers with my hands and felt the familiar gear-changing feeling in my feet. Instead of hearing a subtle “clicking” noise, however, my changing gears seemed to make an extremely loud BANG noise that sounded like a blacksmith hammering an anvil. I panicked! Not only was this a brand new, expensive bike that I might have just broken, but also I couldn’t work out what on earth would have made my gears make such a loud noise. A few seconds after I inspected my chain, gears and pedals to find that everything seemed normal, I realized the experience was just an illusion! I had experienced a variation of the ventriloquist effect.

The ventriloquist effect occurs, for example, when you watch a ventriloquist perform live, and the actor’s voice really seems to be coming from the dummy’s mouth. If you’ve never seen a live ventriloquist performance (like most of the population), then think of every time you have been to the cinemas - the same ventriloquist effect happens: the voices coming out of the speakers around the cinema seem actually to be coming from the on-screen characters’ mouths, right?

The reality of the situation is that the location of the sound source, the cinema speaker for example, is far away from the location of the vision, the image of the person talking. Despite this physical separation of vision and sound, your brain assumes they are a single event because they are happening at exactly the same time and combines them. In the literature, this is referred to as multisensory integration (because information from multiple senses is being integrated, duh). And it makes perfect sense: if there is a flash of light and a crack of sound that occur at exactly the same time, it’s not unreasonable to infer the two are related. Multisensory integration can occur for different combinations of different senses, like vision and sound, vision and touch, and touch and sound, and usually makes it easier for us to perceive and respond to things around us. It’s important to know that the “more clear” sense tends to pull the perceived location of the “less clear” sense closer to it. So when we are at the cinema, the image is so big and clear, whereas we don’t know where the speakers are, so we experience the sound as being pulled towards the vision; we perceive vision and sound as one.

Back to my bike ride! What I finally worked out had happened was that a workman working next to the bike path had dropped a metal rod onto concrete. It was entirely coincidental that the sound of the rod hitting the ground occurred at exactly the same time I felt the gears changing in my feet. Because multisensory integration occurs automatically given the right conditions, my own brain tricked me into thinking the noise I heard came from the same thing that I felt in my feet! Because I didn’t know where the sound was coming from, but I knew exactly where my feet were, the sound got pulled towards the physical feeling. I experienced a ventriloquist effect of the tactile (touch) and auditory (sound) senses. An important distinction to point out is that my experience was “instant”, and made me perceive the noise and feeling as one thing, rather than being an afterthought where I cognitively decided that the two things were related.

When I worked out that I’d had a rather unique multisensory integration experience, I felt a nerdy buzz that allowed me to maintain a constant 30km/h speed on my bike for the rest of my trip! But this experience was especially cool for me because I’ve been working on several multisensory projects for almost two years now. Professor Penelope Sanderson, Matt Thompson and I are currently finishing revisions of a paper summarizing an experiment where people wore a mini computer monitor over one of their eyes while walking around, an experiment that I conducted for my honours thesis in 2008. We showed that multisensory integration of vision and sound seems to occur less when people are walking because of the flow of background visual information that happens when you move your head around. Over last Christmas, I was working with Dr Ada Kritikos on a project investigating the role of proprioception (the sense of where your limbs are in space) in the integration of touch and vision. The project with Ada has spawned a few different follow up experiments, so I can’t write about those paradigms explicitly. Suffice to say the experiments involve fake dummy hands and strangely shaped tools!