The picture below will link you to a quick animation. The blue ring will gradually get smaller until it obscures the three “8”s, then continue to shrink until the figures are visible again. While they are obscured, the 8s will be transformed into letters (S, P, E, U, or H), and a new letter will also appear. Your job is to search for the letter U or H—it has an equal chance of appearing where any of the 8s were, or in the new spot. Click on the picture to try it out.
Attention researchers Steven Franconeri, Andrew Hollingworth, and Daniel Simons used a similar animation to answer a key question about what attracts our attention. Recent research has led to two different hypotheses—either the appearance of a new object, or a change in the luminance (brightness) of an area of our field of view is what attracts our attention.
In many cases, both of these changes occur at the same time. For example, we’re driving down the street and a boy runs out in front of our car chasing a ball. The boy appearing in front of our car is certainly a new object, and the light reflecting off of his sweatshirt carries a different luminance value from the asphalt pavement we had been looking at.
Franconeri and his colleagues cleverly designed the animated display you just looked at to introduce a new object without a corresponding change in luminance: the object was introduced while all four objects were obscured by the blue ring, so when it appeared, there was no luminance change.
In a separate condition, the group presented the same animation, with the ring passing behind the letters, so that when the new object appeared, there was a change in luminance. They repeated the task with 2, 3, and 4 objects in the final display; in each case, participants knew that the 8s would change into letters, and that they’d be searching for a U or an H. Here are their results:
When the ring passes in front of the letters, there is no difference in reaction time, whether the target letter (U or H) appears in a new position or an old position. This suggests that the mere fact of a new letter appearing doesn’t attract our attention, because if it did, we’d react more quickly when the target letter appeared in a new position. Compare this to the control condition, where the letters are always in view:
Now, reaction time is significantly faster for the new item. So when a new item actually changes the luminance of an area in our field of view, we react faster. Franconeri and his team argue that this result supports the luminance hypothesis. They suggest that when the new item corresponds to a luminance change, we direct our attention to that new item. Then we are able to complete the task more quickly—to determine if that item is an H or a U. So a change in luminance attracts our attention, but the appearance of a new object on its own does not.
Franconeri, S.L., Hollingworth, A., & Simons, D.J. (2005). Do new objects capture attention? Psychological Science, 16(4), 275-281.