This study sought to determine whether single-color, "flat" icons would be more quickly and accurately selected by users when presented in either a filled-in or outline style. An application was developed that allowed participants to take a test measuring their speed and accuracy in selecting prompted icons from an array of distractors. The test was made available on the web and was completed by 1,260 participants. Averaged across the 20 unique icon forms used in the test, the outline style led to slightly longer task times, but only when icons were displayed in white against a black background. For individual icons, the effects of icon style were inconsistent and, except for a few exceptions, quite small. This study concluded that one icon style is not objectively better than the other.