In the Ivory Tower literary magazine, student Roger Horrocks wrote of his visit to the Frank Pearson exhibit in 1965:

Entering the University Gallery (that claustrophobic white corridor which reminds me of a ship's passageway), I was overwhelmed by the blaze of color pouring out from a series of diamond-shaped, T-shaped, and upside-down-L-shaped canvases. At first, I approved of the disciplined geometrical forms, but felt very irritated by the color. There appeared to be not the slightest attempt to blend or harmonize different tints, not one painting on which the eye could rest peacefully.

Horrocks did warm up to the paintings eventually, appreciating their optical illusion qualities.
The painter Frank Pearson was a faculty in the University of Minnesota Art Department at the time of his show. Pearson resigned suddenly after only one and a half years on the faculty, and if you'd like to know why, take a look at the Peter Busa entry on this blog and venture a guess...