Purdue Psychological Sciences researcher explores brain’s reaction to pet pics, positive stimuli while examining neurological effects of depression

A picture of your pet, like Raymond the chihuahua here, is an example of positive stimuli used in studies of the late positive potential brain wave and how it processes such images in Purdue University Psychological Sciences Professor Dan Foti’s Psychophysiological Analysis of Cognition, Emotion, and Reward Lab.(Tim Brouk)

Written by: Tim Brouk, tbrouk@purdue.edu

Spilled coffee on your khakis, check engine light blaring bright, laptop possessed by a digital demon again.

But then your phone buzzes. It’s a picture sent by your spouse of your beloved family dog doing something quite precocious. Your mood is instantly elevated.

Dan Foti

Dan Foti, professor in the Purdue University Department of Psychological Sciences, has researched the brain’s reaction to such positive visual stimuli. The mood elevation from seeing your beloved pet may seem immediate, but it takes precious milliseconds for the information to be processed, no matter how cute the photo is.

For numerous projects over the years, Foti invited participants to his Psychophysiological Analysis of Cognition, Emotion, and Reward Lab to strap them up with an electroencephalogram cap before showing them images of puppies, kittens and baby bunnies while measuring their brain activity. For countermeasure, some studies then show images most would find distressing, such as a pit bull ready to attack, a great white shark jumping out of the water toward the camera, or a hungry lion making a kill on the African savanna.

“There’s a particular brain wave that we look at a lot in my laboratory. It’s called the late positive potential, or LPP for short,” Foti said. “This is a particular brainwave that we can use to understand the time course of brain activity millisecond by millisecond.”

Understanding the brain’s process of images could lead to understanding more about the neurological components of people with depression and other mental health conditions. The work also examines emotional reactivity, emotional regulation and coping.

What kind of neurological journey do we take when we see an image of our cherished pet?

If I present you with a very interesting picture or emotionally evocative picture, there’s some early activity in the visual cortex that happens almost instantaneously. And then right around 300 milliseconds after the image comes up on the computer screen, that’s where we see this response called the late positive potential. This is not fine-grained visual processing. This is much more like understanding the stimulus, sort of meaning-making, interpreting the stimulus. Psychologically, it’s getting a handle on “What is this image depicting?” Whereas a lot of that early visual activity is sort of like “How bright is the picture?” Like more fine-grained perceptual properties rather than meaning. I like this brainwave a lot because it has this nice, dynamic course that unfolds over time. And so I can use that brainwave to ask questions such as “How long does this image hold your attention? How deep do you get in terms of interpreting, understanding and making sense of this image?” There are some images that immediately grab our attention, but they don’t hold our attention. There are other images that grab our attention and will hold our attention for several seconds.

How do you know when you find an image worthy of these brain activity studies?

All of the images are of things that generally elicit a response from most people, the kind of image where if you show it to 100 different people, most of those people would say, “Yeah, that’s a pleasant image” or “That is an unpleasant image.”

And there’s certainly things that are uniquely relevant to you based on your life history and what you’re interested in. So, for example, there’s a colleague of mine at another university. He does a lot of this kind of research, but he uses stimuli of delicious desserts. … So, if you’re not hungry — if you just ate a full meal — it doesn’t elicit a response. Or if it’s a dessert that you don’t particularly like. … It doesn’t elicit a response. And so that’s what I mean by a personally relevant stimulus that is going to elicit a strong reaction from you because it’s particularly relevant to your life.

What is an example of a recent project where you used positive stimuli?

One study we did was showing individuals pictures of a stranger’s face versus a celebrity’s face, which should be familiar, versus their partner’s face. And what we were trying to tease apart is “How would looking at the image of your partner elicit this kind of brainwave?” … And the answer is it elicits a massive brain response when you see the face of someone who’s in your life, someone who you care about. Think a romantic partner, think a picture of your own child. Think of your spouse.

How does this work measure for people with depression?

What we tend to see is that (depression) reduces a lot of the different brain waves we measure in my laboratory. It kind of blunts brain activity, and what it’s really blunting is kind of reactivity to the environment. It’s not like their visual system doesn’t work anymore. The basic systems are all intact and working just fine, but it’s kind of blunting the normal reactivity that we would expect. So, for example, one way to measure is to show people these emotionally evocative stimuli, things like happy babies, cute animals or more scary scenes, you know, threatening scenes. For folks who are feeling relatively healthier and in a normal mood state, we tend to see very large neural measures of reactivity, as well as behavioral reactivity and self-reported reactivity and other physiological changes. You could look at changes in heart rate when you look at these images, that kind of thing. But all of that tends to be blunted when folks are depressed. They’re still recognizing it as, “Oh, that’s a puppy; that’s a face; that’s a shark.” There’s that basic recognition of what the image is, but it’s not triggering that more in-depth processing or what we think of as the emotional reaction. And so, I generally talk about it as kind of an emotional blunting.

Folks with depression tend to be less reactive to things in the outside environment, but maybe a little bit more reactive to things that are uniquely relevant to them. So, it’s this kind of biasing of attention. … And so, I think what I haven’t gotten around to doing yet, but I think what someone should do is extend that to looking at other kinds of personally relevant stimuli — including things like faces of loved ones, family members and friends and things like that, and you could extend that to pets as well … How can we map that onto something like a better treatment for depression? Some of the experimental work that we’re doing might get us there someday. And we need a lot of other methods to try to tease apart these different processes. All of this is complicated, but I think there are a lot of interesting questions.