Purpose: To demonstrate that things aren’t always as they seem in everyday encounters with others.

 Time Required: 15 minutes.

 Size of Group: Unlimited.

 Materials Required: A series of optical illusions suggested in part by the book Experimenting with Illusions by Robert Gardner (Franklin Watts, 800-621-1115), which contains a variety of noncopyrighted illusions with lines, 3-D illusions, and magic tricks.

 The Exercise in Action: The human mind is trained to draw conclusions based on what it thinks the eyes see, says Bill Lange, a training specialist at Bank One Columbus, Westerville, OH. But judging anything— people in particular—based on visual input alone can lead to misguided conclusions.

Lange demonstrates by displaying a series of optical illusions, one at a time. He asks the participants to discuss what they think they see before moving on to the next one. He doesn’t offer any explanations until he has shown the entire set. When he’s been through the pictures once, he shows each one again, and explains the trick it plays on the eye.

Lange then ties the lesson to real life: We often judge people based on first impressions. If they appear unkempt, we might assume they’re poor or unintelligent. If they grow verbally hostile, we might assume they’re irrational or belligerent by nature. Conversely, if they dress well, we may conclude they are well mannered or honest. All these presumptions can be wrong.

Lange asks participants to offer possible explanations for any of the above sorts of people not meeting first expectations. A disheveled person, for example, might have just come in from bad weather; a person who seems inordinately angry might have had a bad experience prior to your encounter.

The lesson is a classic: Don’t judge a book by its cover.