Unthinkable_ Who Survives When Disaster Strikes - and Why - Amanda Ripley [60]
The computer, unbeknownst to me, was tracking everything I was doing—not just whether I found the platform. Each time, it measured how long I took to get started, the length of my route, how long I took to find the platform, and how much time I spent in each quadrant of the pool. The test was forcing me to use my hippocampus to orient myself with my short-term memory and contextual cues. The theory is that the better I can do this, the more capable I will be at processing and integrating information during and after a life-or-death situation. Animals that do well on this task also tend to have larger hippocampi.
After the pool test came a much longer and more frustrating pattern test. I had to identify the “correct” one of two patterns in each set. It was surprisingly difficult to place the correct patterns in different contexts. Again, my hippocampal skills were being challenged. Only after about thirty-six different tries did I consistently choose the right pattern over and over. I was hoping Beverlee wasn’t secretly appalled.
Next I sat down with a clinical psychologist for a battery of more old-fashioned tests of memory and IQ. The worn cards and 1960s-era pictures were almost quaint. The psychologist asked me to match strangers’ faces, to put a series of cartoon frames in order, to re-create a shape with colored blocks, to repeat seven different digits—backward—over and over. She said I was doing great, but that was before the animal identification test. I had to name each animal depicted in silhouette on each card, and I was terrible at it. I still would argue about the duck—no duck in nature looks like that, I am telling you—but the truth is I was just miserable at this task.
After six hours, I was wrecked. My brain was clearly not used to this kind of exercise. I don’t even like crossword puzzles. Gilbertson offered me some coffee and then sat me down to discuss the results. He pulled up the results of the pool test from that morning. Men normally do better on these kinds of tests, which measure spatial processing, among other things. “So you’re already working with a handicap,” Gilbertson said. I supposed that was reassuring. He showed me screen after screen of drawings retracing the routes I took to the submerged platform. Some were fairly direct; others look exceptionally loopy. “This is quite good,” Gilbertson said. “It’s actually remarkable. You clearly know where the platform is.”
I figured he was just being nice until he showed me the results of an anonymous combat vet. The vet sometimes got it right, plowing straight toward the platform. But more often, he went round and round, tracing hexagons in the water and sometimes zigzagging back and forth far from the platform. His hippocampus was not reliably making sense of where he was and where he needed to go.
Of course, this was not a fair comparison. I was younger than Gilbertson’s normal participants and female, not to mention the fact that I had never been to war. But for all these reasons, it was especially reassuring that the results were promising.
A week later, Gilbertson got the results of my brain scan. My total hippocampal volume was 7.38 milliliters, or about the size of a small marble, Gilbertson informed me several weeks later. That is significantly larger than the vets with posttraumatic stress disorder. Of course, we are talking about very tiny numbers here. On average, the vets with posttraumatic stress disorder had a hippocampal volume of 6.66 milliliters. So my measurement was only about 10 percent larger. What does this all mean? Well, the implication is that my brain, thanks to the relatively large size of my hippocampus, may be more resilient in certain ways