Remember This: Your Brain Is Cool

I spent much of Friday night and Saturday in the office analyzing data for a study we conducted on in-game advertising (the lead author is Harsha Gangadharbatla, now of the University of Oregon).

During the course of the racing (car) game, participants drove under five billboards. They were not told anything about the billboards, and the idea was to check whether they noticed. We measured physiology to determine whether they were subconsciously noticing (they were), and we later measured their memory to see whether they actually stored the brand names.

First, participants were asked to freely recall the brands that they saw. Performance on this task was not especially good (16%). Later, participants were asked to recognize the brands among other brands in the same product category. Performance on this task was about 40%.

The main points of the study are pretty interesting; however, one little observationt that will not make it in the final paper was pretty interesting.

For each of the five brands, participants could either recall it or not. Furthermore, they could recognize it or not. Obviously, some people were more likely to pay attention to the driving (gamers, it turns out), and some people were more likely to pay attention to the billboards (nongamers, it turns out). Harsha knew this would be the case, but I did not.

For each brand, we could examine whether the probability it was recalled was related to the probability that it was recognized. Perhaps participants good at recall were simply good at recognition.

But this was not the case with our data. For each brand, the probability that it was recalled was significantly correlated with the probability that it was recognized. Furthermore, for each brand, the probability that it was recalled was most strongly related to its own probability of recall.

It could be the case that recalling Brand A was most strongly related to recognizing Brand B -- perhaps even by random chance. But this was not the case. In every case, A was most strongly related to A, and so on.

In many ways, this should be the case. But the fact that it was consistently the case suggests that our measurements of recognition and recall were indeed indexing how well these brands were encoded, stored, and subsequently retrieved from memory.

One kind of memory for each brand was strongly related to another kind of memory for that same brand and only weakly related (at best) to memory for other brands seen perhaps a minute before or after.

When you're trying to understand this limited-capacity attention and memory system of ours, such data are helpful.

Although this, too, will not make it in the paper, visual inspection of the physiological data (cardiac response curves) suggests that participants had an involuntary reflex associated with sensory intake for the brands the recognized but not as much for those that they did not recognize.

This tidbit is pretty awesome, but it will also not make the final paper due to how we analyze data. Although the most appropriate statistical test backs up the "story" told in the preceding paragraph, the highly specialized nature of that particular test makes it seem as if we are being disingenuous in looking for statistical significance. Thus, it is easier to omit than to justify.

All of this continues my respect and love for the human brain. What an amazing device.

Your Heart Tells What Your Brain Knows

One of the academic groups to which I belong, the Society for Psychophysiological Research, started as the Society for Polygraph Research.

It follows that much of the technologies that we use in the lab have some foundation in lie detection.

An important tenet of lie detection is that your body reacts differently depending upon what you know.

Although media portrayals frequently portray lie detection as catching someone telling an untruth, it is more reliable to use the guilty knowledge test.

In this test, an individual is told various aspects of a crime, for example. Some of the details are untrue, and some of the details are things that only someone who had been at the crime scene would know. Thus, if you respond to the proper location of the murder weapon, it suggests that you saw it in that location.

For the first time, my lab is attempting to correlate physiology and memory. I will avoid the details of the experiment here, but we tested memory following presentation of a media-related stimulus. During the memory test, participants heard sound clips that they previously heard during the experiment, and they heard sound clips that they did not hear.

Their job was to say "Yes" they had heard it during the earlier experiment or "No" they hadn't.

We recorded their physiology while they were listening and for several seconds afterward while the screen was black.

We wanted to compare the physiological results based upon their memory performance. Now, I had no idea how much work this would be. Really, it was an insane data analysis. It took forever. There are now more than 12,000 variables in the heart rate data set alone.

In the end, it was worth it, if only for the "cool" value.

The figure above shows a cardiac response curve (CRC) for trials where participants correctly recognized a sound clip (i.e., hits, shown in blue). The second cardiac response curve is for trials where they correctly failed to recognize a clip (i.e., correct rejections, shown in green).

At first, both CRCs show an initial deceleration at the beginning of the trial. This is an orienting reflex elicited by the onset of the trial. However, for the correct rejections, there is sustained cardiac deceleration. We typically associate this sustained deceleration with continued cognitive effort. As your brain tries harder, your heart slows down. Cool, huh?

This makes sense, and it fits with our (and others') model(s) of memory. In a recognition task, you can stop trying as soon as you find a match. That is, when the recognition prime matches a memory, you can confidently feel that you recognized it. Since these trials were correct recognitions, we can assume that the match occurred relatively quickly.

Conversely, when there is no recognition, the brain has to keep trying for matches until you give up. This takes longer, obviously, and should require more cognitive effort. This is the exact picture that we see.

In each case, after we stopped collecting data (which went on for 2 seconds after this figure), participants used a computer mouse to make their recognition decision. Thus, these physiological data precede the recognition decision.

To early lie detectors, these data must seem trivial. Of course there is a difference. To me, however, it is fascinating that your heart beats differently when you recognize something than when you don't.

Quizzing Effect Impacts Memory Interpretations

Every once and a while you read something that changes everything.


The other day I was reading Rob Potter's weblog, and I came across this post about his summer class. In that post, Dr. Potter mentions a Chronicle of Higher Education article on research about the relationship between quizzing and learning.

The underlying study found that the act of quizzing itself impacted learning. It was not that students studied for the quizzes -- it was the thought processes that went on while students tried to answer the quizzes, especially short answer quizzes.

"... Every time you test someone, you change what they know," Washington University psychology professor Henry L. (Roddy) Roediger III told the Chronicle.

The implications are huge.

First, I will likely never teach another undergraduate class that does not employ quizzing. I used to think that it was mean. Now I know that it works.

Secondly, the implications for my research are immediate and direct.

Consider our standard memory testing paradigm. First, we test free recall. That is, we ask participants to recall everything they can remember about the stimulus.

Oops. We already changed them.

Then, sometimes, we test cued recall. We changed them again.

Finally, we test recognition. But we've already changed the memory a lot.

"In the process of retrieving Fact A," said Washington psychology professor Kathleen B. McDermott, "if it takes you a minute to get there, you think, Hmm — what did I learn about this general topic? So in a sense, you're also retrieving Fact B and Fact C, even though that's not what you were directly asked to do."

To his credit, Texas Tech master's student Wes Wise proposed looking at some of his own data to see whether recall predicted later recognition months before the Chronicle story.

I guess that we'll have to run the data now.

High Arousal Evidence for DELCAM Model

One of my passions is studying attention. Most often I talk about paying attention to mediated messages, but the general principles also apply to non-mediated environments.

I have attempted to model real-time human attention and emotion in an artificial neural network, which I have called dynamic, embodied limited capacity attention and memory, or DELCAM. You can read about DELCAM in the current issue of the journal Media Psychology (also read more about DELCAM in this blog posting).

DELCAM was born in 2003 when I tried to formally model Annie Lang's limited capacity model of mediated message processing. Although Lang's model has been instrumental in my thinking, it was difficult to formally implement.

This failed implementation set me back, and I had to spend some quality time with the brain. I had seen enough evidence to believe that attention was limited-capacity, but I needed to spend some quality time with the brain attempting to figure out the nature of this limitation.

Eventually I settled upon the idea of physiological arousal forcing the brain to focus more closely on the central object at hand and less on the periphery. It's a simple idea, really, and it incorporates both common sense and the thinking of several of leading scholars.

Importantly, however, DELCAM correctly predicts that recall increases in arousing contexts, whereas recognition will suffer (again, you can read more about this here).

Because I study mediated messages; however, I do not work at the extreme ends of arousal. Although you get pretty scared watching a horror movie, it does not compare to the horror of having a villain with a knife actually chase you.

In those cases of extreme arousal -- when literally your life is on the line -- what happens to attention. Does it fit with the conceptualization of DELCAM?

I found a partial answer while reading Malcom Gladwell's book, Blink.

Although television shows police officers drawing their guns all of the time, the vast majority of police officers navigate an entire career without ever firing a gun ... ever. So when presented with the necessity to use deadly force, the police officer is in the rarest of circumstances. And afraid for her or his life.

The sympathetic nervous system surges, and the heart pounds as if it will tear through the chest.

Here's Gladwell quoting a police officer in David Klinger's book, Into the Kill Zone.

When he started toward us, it was almost like it was in slow motion and everything went into a tight focus ... When he made his move, my whole body just tensed up. I don't remember having any feeling from my chest down. Everything was focused forward to watch and react to my target. Talk about an adrenaline rush! Everything tightened up, and all my senses were directed forward at the man running at us with a gun. My vision was focused on his torso and the gun. I couldn't tell you what his left hand was doing. I have no idea. I was watching the gun. The gun was coming down in front of his chest area, and that's when I did my first shots.

I didn't hear a thing, not one thing. Alan had fired one round when I shot my first pair, but I didn't hear hm shoot. He shot two more rounds when I fired the second time, but I didn't hear any of those rounds, either. We stopped shooting when he hit the floor and slid into me. Then I was on my feet standing over the guy. I don't even remember pushing myself up. All I know is the next thing I knew I was standing on two feet looking down at the guy. I don't know how I got there, whether I pushed up with my hands, or whether I pulled my knees up underneath. I don't know, but once I was up, I was hearing things again because I could hear brass still clinking on the tile floor. Time had also returned to normal by then, because it had slowed down during the shooting. That started as soon as he started toward us. Even though I knew he was running at us, it looked like he was moving in slow motion. Damnedest thing I ever saw (Blink, pp. 223-224).

DELCAM suggests that limited-capacity cognition allocates attention toward the "target" as physiological arousal increases (an ironic choice in terminology, as it turns out). This police officer's recount suggests that this reallocation can continue along a continuum until superfluous channels -- in this case audio -- are altogether removed from conscious processing.

Come on Horse, Let's Go for a Ride

Photo credit: Unknown.

---

Today I was sitting having lunch at the brand new Jimmy John's with master's student Wes Wise.

I grew to love Jimmy John's at Indiana, and I was glad to see one open up near the Tech campus.

While enjoying my #5, I saw a horse driving down Broadway Ave. Sticking out of the window was the head of a live Shetland pony.

Wow. Wes and I remarked at the oddness and carried on.

About 10 minutes later it clicked. I had seen that fool pony before. In an e-mail sent around last summer with a title something like "Only in Lubbock."

I found the picture. And sure enough. Same pony.

Welcome to Lubbock. The Giant Side of Texas.

Yes, No, Audition, and the Human Brain

First, let me offer "mad props" to Adobe for their wonderful software, Audition. My copy arrived Friday, and I already love it.

I spent Saturday in the lab editing audio instructions generously recorded by my colleague, Todd Chambers, Ph.D. I was trimming the edges of the files and getting rid of breathing pauses.

As I have mentioned before, I grew up around a family advertising agency, and I cannot tell you how many hours I have spent in a recording studio. I still get a special nostalgic feel when I hear the high pitched "chirp" of video tape getting up-to-speed or slowing down.

Along the way, I also learned some things. Before his advertising career, my dad (also named Sam Bradley) was a radio man. So I have heard great stories about his radio career. Enough so that I began my career as a broadcast journalism major at New Mexico State.

Although that career did not last long, I did gain experience editing analog recordings (although I had nothing that could be called skill), and I even actually taped some audio tape together.

Over the years, I actually learned a thing or two. I can recall dad talking about how much easier it is to remove pauses and breaths in the digital world. And it was this that led me to cleaning up Todd's recording in Audition.

As perhaps only a hopeless academic is apt to do, I noticed something scientific while I was editing. Admittedly it is only a tangential little linguistic phenomenon of interest to scientists, but pretty darned cool to me nonetheless.

Permit me one more digression, and I will explain.

When I first arrived in Bloomington in January 2002, I happened across an article by world-famous IU psychologist, Richard M. Shiffrin (see full citation below). In that study, they used audio to record answers to memory questions. Participants either were to acknowledge "yes" they had seen the material or "no" they had not.

They used a computer to record response times, or how fast it took people to say "yes" or "no." And when you're keeping track of time, you need things to be on an even playing field. And it seems that all things are not equal with "yes" and "no."

In order to make them equal, they had participants say the letter "P" first. So they said "P-yes" and "P-no" instead of "yes" and "no."

Nobel and Shiffrin (2001) wrote, "The 'P' sound was inserted at the beginning of the verbal response to equate the onset times for different phonemes. Differences as large as 150 ms in initial phonemes have been reported (see, e.g., Pechmann, Reetz, & Zerbst, 1989)."

For some reason likely due to me being a nerd, this stuck with me.


While editing Todd's recordings Saturday, I noticed a difference between "yes" and "no" that illustrated the very reasoning behind "P-yes" and "P-no."

It takes "no" longer to get up to full volume than "yes."

Too cool!!!!

I do not have copies of Todd's recording here, so I quickly recorded myself saying "Yes" and "No" and imported those into Audition. With roughly equal onset times, you can see that "Yes" (above) ramps up much more quickly than "no" (below).

To me, this is very, very cool. First, the cognitive processing of phonemes is of great interest. This difference suggests that humans are able to understand the word "yes" more quickly than "no." Interesting, perhaps.

But also cool is that is was quicker to record and edit these audio clips than it was to write this posting. Some days, I hate technology. But most days it is pretty damned cool!

---

Nobel, P. A., & Shiffrin, R. M. (2001). Retrieval processes in recognition and cued recall. Journal of Experimental Psychology: Learning, Memory, and Cognition, 27, 384-413.