Doors of Perception

The perception of the human mind has long been a topic of intrigue and bewilderment. In this issue of Search + Discover, University of Minnesota faculty tackle the questions of:

• why time seems to pass more quickly when we grow older
• whether I see colors as you see colors
• what are blind people's dreams like

Plus, you can explore further reading and related links.

Why is it when we grow older, time seems to pass more quickly?

“The feeling that time passes more or less slowly in different situations—and in different eras of our lives—is a central issue in time perception research. One explanation for why time seems to pass more swiftly as we age is that we have less time to pay attention to the passage of time itself. In other words, when one is occupied with other matters, time appears to pass quickly, while when one pays more attention to time, it seems to pass slowly. This concept is played out in our everyday lives, for example, when we continually check the clock in the expectation of the end of class, and ten minutes can feel like 30.

“When we’re young we have plenty of free time, a good portion of which (particularly during summer vacation) is spent looking for something to do, so time seems to pass slowly. As we age, we lose the benefit of enormous tracts of free time and instead fill our days with a wide range of activities that can distract us from monitoring the passage of time, so time seems to pass more rapidly. Unfortunately, the only apparent solution to this problem is to pay more attention to time by abandoning the ‘distracting’ activities that are making life appear to pass so quickly!

“While clearing your schedule to spend more time thinking about time may be a bit extreme, everyone should be thankful as they age for those precious moments of boredom, for only then can time once again stand still.”

—Ben Denkinger, Ph.D. candidate, Department of Psychology

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Is my blue your blue? Do I see colors as you see colors?

“This intriguing question about color lies at the heart of the interesting and long-standing philosophical question of whether we can know what others (and even animals) actually perceive.

“A skeptic once said, ‘I know nothing about your sensations except what your behavior tells me.’ We can, of course, try to describe our sensations in words to someone else, and usually don’t think that this is much of a problem. This approach, called introspection by the philosophers, can be described as ‘looking into your mind and describing its contents.’ So what’s the problem?

“If we ask two people what the color of the sky is, they will probably both say ‘blue.’ Yet as artists and the rest of us know, there are many subtle shades of blue. If we then ask these people to use more detailed color names, suppose they now both say ‘azure blue.’ Do we know that they see exactly the same ‘blue’ or that they actually see different shades of ‘blue’ but have a limited vocabulary (like most of us) to describe fine differences in perceived color?

“This is a dilemma.

“In the laboratory, over the last 80 years, psychologists and color scientists have obtained a large body of precise measurements of the ability of human observers to discriminate colored lights. Except for color blind people, the results of these precise measurements are very similar from one person to the next.

“So we now have strong scientific evidence for concluding that color perception is similar from one person to another. But is it identical? Is the blue that you see, the same blue that I see?

“Modern technology in eye and brain research is remarkably advanced and yet the measurements are much too crude to prove that two people have identical sensations.

“So we are left with one of those universal and fascinating questions--in some ways all the more fascinating because we cannot yet provide an answer and perhaps never will.

“In sum, ‘Is my blue your blue?’ Perhaps, but no one knows for sure!”

—Dwight Burkhardt, professor, Department of Psychology

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Dreams tend to be visual, so what are blind people’s dreams like?

“It depends on when the person became blind. People blind from birth, who have never had a visual experience, will not have color dreams. But much of dreaming is about spatial environments and can include sounds and tactile (touch) sensations, so their dreams can be quite vivid; the only things lacking would be color and other visual elements. The dreams of people who became blind after some years of vision, or people with reduced vision, vary in the amount of visual content. There is often loss of visual vividness over time, but studies imply that some people retain very vivid visual elements. For others, those fade away.”

—Gordon Legge, Distinguished McKnight University Professor and chair, Department of Psychology

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