Thursday, September 24, 2009

Remembering the Bad Along With the Good

In my Sept. 15, blog I surveyed an experiment that showed people learning more from their successes than from their failures. In so doing, I raised the possibility that the learning gain was promoted by the release of the "reward transmitter," dopamine. Now I find a new research report on the effect of dopamine on the long-term storage of bad memories. The process studied was the long-term memory of fear and pain. Rats were trained to remember a strong foot shock, which lasted at least 14 days. Injecting a dopamine blocker into the hippocampus erased the long-term memory if given 12 hours after the original foot-shock experience. This suggests that the normal release of dopamine can promote memory, which is not surprising since dopamine promotes the formation of proteins used in synaptic junctions of neurons.

However, foot shock is certainly not rewarding and probably does not release dopamine. But the end of the foot shock pain is a rewarding relief. Also, rewarding things do happen even to rats after a nasty foot shock (like sex with mates, eating, drinking, sleeping, etc.). The ongoing release of dopamine in the course of just living may help rats form lasting memories, regardless of the nature of memory. This raises questions that scientists have not studied yet. But it may be that dopamine helps us remember both the good and the bad. And maybe is one reason why bad memories are hard to erase.

Source: Rossato, J. et al. 2009. Dopamine controls persistence of long-term memory storage. Science. 325: 1017-1020.

Tuesday, September 15, 2009

Why The Rich Get Richer

... (and the Smart Get Smarter)

This old saying also has a corollary: the poor get poorer (at least relative to the rich). Of course there are exceptions, but these correlations happen often enough to indicate there is some truth to the saying. I never heard anybody explain this, other than to conclude that life is just unfair. But there is an explanation.

The reason is that the rich learn from their successes, while the poor, who don’t have many successes, fail to learn from their failures. And the reason for that is that the human brain is wired to learn better from success than from failure. It all has to do with the positive reward system in the brain. Practically speaking, the most obvious example is how animals are trained for circus performances, how dogs are trained to sniff out drugs or corpses, and the like. Positive reinforcement when they do things right promotes learning more effectively and faster than punishing them when they do things wrong. Apparently, the same principle holds for people.

A report of a study of nerve cell activity in monkeys showed sustained, persistent outcome-related responses in both prefrontal cortex and in the basal ganglia, areas known to participate in learning stimulus-response associations. These neurons keep track of successes and failures over many seconds, which is long enough to form a semi-permanent memory that can affect the response the next time such a learning opportunity arises. The neural response improves after a recent success, but doesn’t improve as much after a recent failure. Not surprisingly, monkeys that were rewarded for the right resonse to a cue learned quickly how to respond the next time they saw the cue. But monkeys that responded incorrectly weren’t any better able to deal with the same cue the next time they saw it.

The authors speculate that successes are more informative than failures. When you fail, you typically already know why and there is not much new to learn. Why then do we keep making the same mistakes? I suspect that habit and emotional factors have a lot to do with it. Compulsive gambling and drug abuse are classic examples of repeatedly doing what you already know is wrong. I remember when I tried many times to quit smoking I only succeeded long term when I took up jogging, which is accompanied by the positive reinforcement of endorphins.

I also suspect that a major reason you learn more from success than from failure is the power of the brain’s dopaminergic and endorphin reward systems. Not only does positive reinforcement feel better emotionally than punishment, there is a real possibility that the dopamine release associated with reward has a direct biological influence on memory formation.

Histed, M. H., Pasupathy, A., and Miller, E. K. 2009. Learning substrates in the primate prefrontal cortex and striatum: sustained activity related to successful actions. Neuron. 63 (2): 244-253.

Motivation Comes In First

Laura, of "Dr. Laura" fame posted in her blog an item about how some students are paid money for doing well in school. Her blog referred to a Fox News item about a school district that was using financial rewards to motivate students to get good grades. ... Why would MONEY make the difference, and not the appreciation of their parents, the respect of their peers, the approval from their teachers, or the mere burst of pride in doing well? The answer is simple: kids these days are not raised to care about appreciation, respect, approval and pride…period! They are brought up to care about celebrity, extravagance, notoriety, freakish attention (think reality shows), infamy as a positive experience, and extreme non-conformity to traditional values. What happens to these kids when the money isn’t there, but there is still the expectation of profound effort and commitment? Certainly teachers, police, firefighters, those in the military, and small shop owners (to name just a few) aren’t putting out their best efforts for the financial reward. A police officer who “collars” a serious bad guy gets a lot of thumps on the back, a night of some beers with fellow colleagues, and a notch toward an eventual promotion in rank. Mostly, he has pride in doing his job well. ... Schools have been eliminating accolades such as high honors at graduation (e.g., valedictorian) so as not to hurt the self-esteem of those who won’t or can’t rise to that occasion. Yet, they want to give money, money, money to those who do. What is THAT message? No one’s feelings are going to be hurt because they didn’t get the money, money, money. Ugh."

I say "Ugh" too. At the heart of the school problem is that so many kids do not take pride in their work. How do you suppose that translates when they get out of school and on the job? I would argue that the most valuable lesson one can learn in school is to take pride in one's work. This story reminds us all that when it comes to learning, motivation may not be everything, but it is way ahead of whatever is in second place (which is probably poor memory skills). I have been teaching for almost 50 years, and I can tell you that positive motivation can overcome bad teachers, bad textbooks, boring subject matter, and almost any obstacle to learning you can think of. Conversely, no matter how hard a school or teacher may try to provide a good learning environment, good student performance is not going to happen without motivation. If people want to learn badly enough, they will surely find a way. True, a few academic subjects may be too advanced for a given level of IQ or pre-requisite learning. But even the slow of wit can learn a lot more than most people think. It may just take longer.

Source:Readin’, ‘Riting, and ….Bribing? June 11, 2009 on 10:32 am In Children, Education, Parenting, Values . Dr. Laura's Blog