As many children, along with their parents, well know, finding Waldo takes work, not to mention a goodly amount of patience.In the popular series of children’s books, readers are challenged to pick out the protagonist from a sea of other faces. It easily can take minutes, and often much longer, to zero in on the character.Anyone who has been left feeling a little visually challenged by the search can take comfort. Researchers have concluded that, indeed, such tasks are just plain hard. In December, the online Journal of Vision published a special issue on the phenomena of vision and “crowding.” Among the 25 topics covered was why people have trouble picking out a single face in a crowded setting.Researchers from the University of California, Davis, found that the failure to recognize a face quickly in a crowded environment, even if it belongs to a loved one, is typical. When confronted with a barrage of stimuli, the human brain reverts to shortcuts to sort quickly through piles of information in a matter of milliseconds. To test their theory, the investigators conducted a series of experiments to see how quickly participants could recognize a familiar face or a house that was placed amid a series of other faces or houses. They found that face recognition is impaired when the target is surrounded by other upright faces (as would happen in a crowd). The researchers concluded that the upright faces interfere with one another as they are being processed by the viewer because faces are processed holistically. Other objects, such as houses, are processed as a series of lines and edges. Participants had less trouble picking out a target house from a larger group.The work could have implications for those with face-recognition or visual attention-related ailments.