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Sunday, February 8, 2009

In games, brains work differently when playing vs. a human

By John Timmer

In games, brains work differently when playing vs. a human

At its simplest, winning most games comes down to one thing: outsmarting your opponent. One of the appeals of networked games, however, is that doing so is generally considered to be much more challenging when your opponent is a human instead of a machine. Even the best algorithms can fall into predictable patterns, and few of them are able to recognize any habits that human players fall into. A new, open access study describes how the brain activity of subjects changed based on whether they thought they were playing a human or not, and that this difference is influenced by the sex of the subject.

The paper itself has a provocative title, starting with the question, "Are women better mindreaders?" The answer, I'd argue, isn't actually contained in the text, which appears to suffer a bit from some overinterpretation of the data and a discussion that casually accepts some gender clichés. Nevertheless, the basic data appear to be solid, even if their interpretation isn't.

Those data were obtained fairly simply. A dozen males and an equal number of females were subjected to functional MRI scans, which can identify areas of the brain that are active during a given process. In this study, the process was a game, the generalized form of the Prisoner's Dilemma, in which two players get rewards for cooperation while facing the constant lure of gaining at the expense of your opponent. In every case, the subject was actually pitted against a computer opponent that was programmed to make its choices randomly but, in half the tests, the subjects were told they were playing another human.

This gave the researchers the opportunity to compare the two circumstances. Average the two sets of results, and then subtract the areas activated in the human vs. computer situation from the human vs. (fake) human data—the end result should be an identification of any areas of the brain that are activated when people think they're facing a human opponent. In this case, the areas that this process identified are the anterior cingulate cortex, the temporo-parietal junction, and the medial prefrontal cortex.

These areas appear to be involved in, among other things, what the authors use their title to call "mind reading." More formally, they seem to be activated when individuals are trying to comprehend the mental state of another person, in essence projecting a person's own conscious decision making process into another individual in order to evaluate their thoughts. So, in the authors' view, this fits in nicely with their expectations: playing a human causes people to construct a picture of their opponent's mental state.

Unfortunately, that "among other things" is a serious problem here. The human brain appears to try to parse the intentions of others by engaging its own decision-making process; in short, it appears to model another person's mind by seeing what it would do if it were in that other person's skull. The three areas of the brain that the authors identify are involved, in part, in making executive decisions for that brain's owner, in addition to evaluating other people's executive decisions. So, the fact that they're busier when a person thinks they're playing another human could also be interpreted as them focusing harder on an identical decision making process.

Where do the sex differences come in? It turns out that, if you bin the data based on sex and then perform a similar subtraction, male brains seem to be working a bit harder than their female peers, which the authors interpret in light of the female gender's reputation for being more empathetic. Again, this seems open to alternate interpretations (based on alternate clichés), like it lining up with the reputation of males being focused on winning games.

Even though the authors focus on a subset of potential interpretations despite the fact that there appear to be equally valid alternatives, the underlying data appears solid, and nearly all the interpretations appear pretty interesting. Why would humans either need or feel compelled to think harder about playing against another human when the game really involves only pattern matching? Designing the experiments that distinguish among them should prove an interesting challenge, and one I hope to be able to read about in the future.

Original here

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