Religious beliefs shape perception of stimuli

Nicholas C. DiDonato

A Calvinist and a Catholic walk into a bar. The bartender says, “What’ll ya have?” The Calvinist, whose theology has inclined him to think individualistically, picks an obscure beer, while the Catholic just says, “I’ll have that too.” While that joke may fall flat, it does reflect leading research about how religious practice affects mental processing. A group of psychologists led by Bernhard Hommel of Leiden University has recently found that neo-Calvinists tend to process information more individualistically, while Catholics process more collectively.

Astonishingly, the researchers theorized that theology can shape not only reasoning but perception itself. Neo-Calvinist theology emphasizes individualism, and as such neo-Calvinists should display a bias toward local perception. That is, they should notice the local aspects of events. By contrast, Catholics, with their theological collectivism, should notice the global aspects of events.

To test this, the psychologists gave both neo-Calvinists and Catholics a Simon task. A Simon task displays spatially well-defined objects (in this case, arrows) and spatially arbitrarily-defined objects (in this case, colors). Typically, people respond faster to the well-defined stimuli than the arbitrarily-defined stimuli. For instance, suppose a Simon task asks its participant to press a button corresponding to “left” or “right” depending on the stimulus. Two of the stimuli indicate left, one naturally (a left arrow), and one arbitrarily (the color blue), and two indicate right (a right arrow and the color green). Researchers would expect the average person to respond much faster to the arrows than to the colors, and this difference in response time defines the Simon effect.

Neo-Calvinists, then, should display a reduced Simon effect because of their locally-biased perception, while Catholics should display an increased Simon effect due to their globally-biased perception. Since theological belief should decide the difference, the researchers selected atheists as the control group for both neo-Calvinists and Catholics.

In the first experiment, neo-Calvinists and atheists, after being matched for ethnicity, culture, age, and IQ, took a Simon test on a computer. The researchers told the participants to respond as quickly as possible but also to keep their error rate below 15%. As expected, the neo-Calvinists had a smaller Simon effect than atheists.

Still, religion in general, rather than any particular theology, may account for the Simon effect discrepancy between neo-Calvinists and atheists. To control for this, the researchers tested Catholics, hypothesizing that their collectivist theology would not only not result in an decreased Simon effect, but would actually increase the effect.

Once again, the experimenters match Catholics and atheists for ethnicity, culture, age, and IQ. They conducted the same exact Simon test they performed on the neo-Calvinists. Sure enough, Catholics exhibited a greater Simon effect than atheists. Perception and mental processing seem not to depend on religion in general but on the content of that religion’s theology and practice.

Further desiring to pinpoint the source of difference in the Simon effect, the researchers issued a stop-signal task to all participants. They anticipated that neo-Calvinists might have a reduced Simon effect because their religion has trained them to have superior response inhibition. That is, like the Puritan stereotype, neo-Calvinist culture may cultivate strict discipline and self-control. Perhaps this accounts for the reduced Simon effect.

A stop-signal task creates a situation that demands intense focus (in this case, pressing an arrow key in the same direction of the arrow key on-screen at break-neck speed) and then abruptly stopping and restarting the task. The computer keeps track of participants’ failed attempts to stop. In short, the stop-signal task measure inhibition.

Neither the neo-Calvinists, Catholics, nor atheists performed unusually well or poorly on the stop-signal task. It appears that religion, at least in this experiment, does not affect inhibition.

Some may continue to resist the implication that theology and religious practice impact perception and reasoning. They may feel that those who think individualistically become neo-Calvinists while those who think collectively become Catholics. To this, the researchers argue that, for their subjects (Europeans), religion tends to be inherited, and, furthermore, genetic dispositions towards certain modes of perception require a social environment. That is, someone who thinks individualistically does so not simply because of their genes but because of a host of other factors (including environment).

It seems plausible to conclude that theological belief and practice may have a deep effect on how people think and perceive. Going to church appears to shape not only spiritual life but also more worldly facets of life.

For more, see “Religion and action control: Faith-specific modulation of the Simon effect but not Stop-Signal performance in the journal Cognition.