Remember Tetris? The seemingly simple game where one must try to create an unbroken horizontal line while different shapes fall from the top of the screen?

Well a study at Harvard medical school’s Department of Psychiatry paid subjects to play Tetris for multiple hours a day, over several consecutive days. The aftermath of this amount of gaming resulted in participants dreaming about Tetris and literally seeing the world as one big Tetris opportunity for days afterward.

One addict said, “Walking through the aisles at the local Acme, trying to decide between Honey Nut or the new frosted Cheerios, I noticed how perfectly one set of cereal boxes would fit in with the gap on the row below it.”1

Others expressed similar sentiments when seeing a brick building. No, these gamers are not insane. What happened to them is a physical process that gets triggered in the brain when playing a game for repeated hours. “The cognitive pattern caused them to involuntarily see Tetris shapes wherever they looked…it actually changes wiring in the brain,” writes Harvard Professor Shawn Achor.

“This phenomenon explains how our brain can get stuck into patterns of viewing the world, some more beneficial than others,” Achor says. “In other words, this is a metaphor for how our brains dictate the world around us.”2

Our brain acts as a massive filter of information and has the capacity to only focus on a certain amount of input at once. About 90% of what we feed our brain from external stimulus gets put into “spam.” If it’s not pertinent, we not only don’t remember it, we don’t even “see” or experience it.

The famous psychological study where participants watch a basketball-tossing game hammers this point. Participants were tasked with determining how many times the “white shirt” team passed the ball. Half a minute into the video, a man wearing a gorilla costume walks blatantly across the screen for five seconds. After the video, the participants were asked, “Did you notice anything out of the ordinary in the video? Did you see the gorilla?”

Almost half (46%) did not see the gorilla at all! They requested to see the video again, disbelieving that it could have been there. After watching the video a second time, they were dumbfounded by how oblivious they had been.

This phenomenon is called inattentional blindness, or selective perception. It also explains why when you purchase a new car, you suddenly see that model everywhere. What we focus on is what we see.

Essentially, whatever our mind doesn’t use gets immediately filtered. If we don’t have use for negative perceptions, those perceptions will get thrown out. The more we play Tetris, the more we see Tetris. The more we seek good, the more we will automatically see good.

Since this applies to anything we invest energy in, we can create a positive “Tetris effect”. The more we “play” gratitude, the more we see joy while simultaneously filtering out negativity because our brain realizes, “It’s of no use to us.”

Wiring our brain to see the good in others can strengthen our marriage and increase our daily happiness.

This is how gratitude journals help prune our minds to be more positive. Such journals can take many forms, but one way to incorporate the concept is by asking ourselves and family members to identify three positive experiences from the day. Doing this not only creates a warmer atmosphere at the dinner table, during the bedtime routine, or throughout the car ride home, but it forces our brains to preemptively scan our days to look for the positive, while simultaneously filtering out smaller annoyances (i.e. the gorilla walking across the screen).

Using the science behind selective perception can help us become master thinkers of positivity. When we practice seeking out the positive in our lives and actively expressing gratitude, our minds become skilled at weeding out negativity. In this way, when a negative thought pops up, our minds will swiftly prune it and move on to more positive thinking.

1. Shawn Achor, The Happiness Advantage, pg. 88
2. Shawn Achor, The Happiness Advantage, pg. 90-91