Saturday, August 7, 2010

Cortisol, surprise-enhanced cognition, and flashbulb memories: Scaring people with a snake screen and getting a PhD for it!

Cortisol is a hormone that has a number of important functions. It gets us out of bed in the morning, it cranks up our metabolism in preparation for intense exercise, and it also helps us memorize things and even learn. Yes, it helps us learn. Memorization in particular, and cognition in general, would be significantly impaired without cortisol. When you are surprised, particularly with something unpleasant, cortisol levels increase and enhance cognition. This is in part what an interesting study suggests; a study in which I was involved. The study was properly “sanctified” by the academic peer-review process (Kock et al., 2009; full reference and link at the end of this post).

The main hypothesis tested through this study is also known as the “flashbulb memorization” hypothesis. Interestingly, up until this study was conducted no one seemed to have used evolution to provide a basis on which flashbulb memorization can be explained. The basic idea here is that enhanced cognition within the temporal vicinity of animal attacks (i.e., a few minutes before and after) allowed our hominid ancestors to better build and associate memories related to the animals and their typical habitat markers (e.g., vegetation, terrain, rock formations), which in turn increased their survival chances. Their survival chances increased because the memories helped them avoid a second encounter; if they survived the first, of course. And so flashbulb memorization evolved. (In fact, it might have evolved earlier than at the hominid stage, and it may also have evolved in other species.)

The study involved 186 student participants. The participants were asked to review web-based learning modules and subsequently take a test on what they had learned. Data from 6 learning modules in 2 experimental conditions were contrasted. In the treatment condition a web-based screen with a snake in attack position was used to surprise the participants; the snake screen was absent in the control condition. See schematic figure below (click on it to enlarge). The “surprise zone” in the figure comprises the modules immediately before and after the snake screen (modules 3 and 4); those are the modules in which higher scores were predicted.

The figure below (click on it to enlarge) shows a summary of the results. The top part of the figure shows the percentage differences between average scores obtained by participants in the treatment and control conditions. The bottom part of the figure shows the average scores obtained by participants in both conditions, as well as the scores that the participants would have obtained by chance. The chance scores would likely have been the ones obtained by the participants if their learning had been significantly impaired for any of the modules; this could have happened due to distraction, for example. As you can see, the scores for all modules are significantly higher than chance.

In summary, the participants who were surprised with the snake screen obtained significantly higher scores for the two modules immediately before (about 20 percent higher) and after (about 40 percent higher) the snake screen. The reason is that the surprise elicited by the snake screen increased cortisol levels, which in turn improved learning for modules 3 and 4. Adrenaline and noradrenaline (epinephrine and norepinephrine) may also be involved. This phenomenon is so odd that it seems to defy the laws of physics; note that Module 3 was reviewed before the snake screen. And, depending on the size of a test, this could have turned a “C” into an “A” grade!

Similarly, it is because of this action of cortisol that Americans reading this post, especially those who lived in the East Coast in 2001, remember vividly where they were, what they were doing, and who they were with, when they first heard about the September 11, 2001 Attacks. I was living in Philadelphia at the time, and I remember those details very vividly, even though the Attacks happened almost 10 years ago. That is one of the fascinating things that cortisol does; it instantaneously turns short-term contextual memories temporally associated with a surprise event (i.e., a few minutes before and after the event) into vivid long-term memories.

This study was part of the PhD research project of one of my former doctoral students, and now Dr. Ruth Chatelain-Jardon. Her PhD was granted in May 2010. She expanded the study through data collection in two different countries, and a wide range of analyses. (It is not that easy to get a PhD!) Her research provides solid evidence that flashbulb memorization is a real phenomenon, and also that it is a human universal. Thanks are also due to Dr. Jesus Carmona, another former doctoral student of mine who worked on a different PhD research project, but who also helped a lot with this project.


Kock, N., Chatelain-Jardón, R., & Carmona, J. (2009). Scaring them into learning!? Using a snake screen to enhance the knowledge transfer effectiveness of a web interface. Decision Sciences Journal of Innovative Education, 7(2), 359-375.


Pål Jåbekk said...

Congrats to your students, Ned! Really interesting function of cortisol and fantastic that it enhances memory of what is already experienced although i can see how this makes sense in an evolutionary perspective.

LeonRover said...

Yeah Ned, that is a nice result - for both of you.

Was any brain imaging possible with any of the subjects possibly showing Nuclear Accumbens activity?

Back briefly to The China Study. Had you thought of using any of Lindeberg's Kitava data as an extra Chinese county and find out which, if any, correlations might be enhanced or diminished?

Ned Kock said...

Hi Pal, thanks.

We have discarded mini time travel or a quantum mechanics phenomenon as possible explanations for the increase in Module 3. But we never know!

Ned Kock said...

Hi Leon.

No brain imaging in this study. Good point, NA activity might have been involved. I think some folks found that the placebo effect is related to that area of the brain.

It would be interesting to analyze the Kitava data, but perhaps it would be wiser to do the analysis separate from the China Study data.

I am thinking about doing some additional analyzes on the data that has made available. But first I need to find a way of warping space-time so that I can travel to another dimension and spend 10 h there while only 1 h passes here. I know I can do that by traveling at a speed that approaches the speed of light, but it sounds expensive!

LeonRover said...

If you want to travel within 10 dimensions I guess you may to find a quantum gravity wormhole a la Hawkings or un-ravel some Smolin or Woit "strings"!

Re: Lindeberg & Kitava. Some curiosities

i) As far as I know he did not do a Weston Price type approach and look at dental health or other health markers.
ii) The heavy smoking & its seeming lack of influence on lung ill-health has not been explored.
iii) His comparisons of his pseudo-Paleo and Swedish/SAD diets INCLUDES a breakout of alcohol KCals - very Nordic, about 4%.

Ned Kock said...

Hi Leon.

I have watched this video recently where these folks live long lives, and many smoke:

My impression is that they don't inhale though.

Jim Sutton said...

Hi Ned,
The video suggesting hyaluronic acid having a role in longevity, health, and appearance led me to do some quick searching.

Came up with
"These results suggest that subcutaneous adipocytes influence dermal condition by up-regulating collagen and HA production by dermal fibroblasts via secretion of adiponectin and leptin." at

And, "Together, these results suggest that linoleic acid seems to interfere with other insulin signalling pathway different from those controlling glucose uptake and metabolism, but involved in the regulation of leptin and adiponectin production." at

The Wikipedia entry for the Snidely Whiplash of fatty acids says, "a polyunsaturated fatty acid used in the biosynthesis of arachidonic acid (AA) and thus some prostaglandins. It is found in the lipids of cell membranes. It is abundant in many vegetable oils, comprising over half (by weight) of poppy seed, safflower, sunflower, and corn oils.[4]"

Makes me want to know more about what those folks have eaten for so many years.

Ned Kock said...
This comment has been removed by the author.
Ned Kock said...

Hi Jim.

This also reminds me that linoleic acid is one type of omega-6 fat, of which industrial vegetable oils (e.g., safflower, corn) are a very rich source.

Apparently the (arguably) longest-living group in the world, the Okinawans, consume plenty of pork. Pork is a staple of their traditional diet:

Yet pork is a poor source of linoleic acid, even though it is rich in omega-6 fats. The average cut will have > 10 times more omega-6 than omega-3.

Monica Kock said...

HI DADDY!!!!!!!

i don't get more than half of what you wrote, but snakes creep me out! they're bleh!!!!!

oh yeah, i own your blog!

Jim Sutton said...

Thanks for the reply, Ned. Yes, I knew about the Okinawans. I actually ate with an Okinawan family back in about 1966. Unfortunately I don't remember what we ate, except for one thing: sliced raw okra sprinkled with what I think was soy sauce. I still eat it occasionally prepared that way.

Those links I referenced, though hardly a 'scientific study', show that the body's own supply of (or dietary sources of high molecular weight) hyaluronic acid is useful for maintaining joint health and skin quality, but is severely reduced by LA because of it's negative effect on adiponectin and leptin. Makes me wonder how their diet differs from the Oki diet, and if the Okinawans, though long-lived, are as spry and smooth-skinned.

The Wiki entry, even though identifying the sources of O-6 as 'vegetable', has a very good table of the worst offenders. All are from seeds, of course, some grass seeds and some fruit seeds. Grapeseed oil is 'the pits'.

Ned Kock said...

Hi Jim.

The story regarding hyaluronic acid (a.k.a. hyaluronan) is complex. There are quite a few reports of it being a cancer-promoting agent. See this one, for example:

I think there are several factors involved, and the relationship between those positive health factors (described in the YouTube clip) and hyaluronan is a complex one.

Maybe there is something else (diet, lifestyle, genes) that promotes health among those folks and is also associated with high hyaluronan levels.

And of course it is also possible that hyaluronan is used by the body to fight cancer, which is why it is found to be "strongly associated" with cancer. A bit like cholesterol, in a sense.

Ned Kock said...

Yes Monica, you own the blog, but I still do the posting :)

Anonymous said...

but memory is a tricky thing see this