Steven Pinker -- How the Mind Works - Hampshire High Italian ...

288 | HOW THE MIND WORKSO, who can hold a fire in his handBy thinking on the frosty Caucasus?Or cloy the hungry edge of appetiteBy bare imagination of a feast?Or wallow naked in December snowBy thinking on fantastic summer's heat?Clearly an image is different from an experience of the real thing.William James said that images are "devoid of pungency and tang." Butin a 1910 Ph.D. thesis, the psychologist Cheves W. Perky tried to showthat images were like very faint experiences. She asked her subjects toform a mental image, say of a banana, on a blank wall. The wall wasactually a rear-projection screen, and Perky surreptitiously projected areal but dim slide on it. Anyone coming into the room at that point wouldhave seen the slide, but none of the subjects noticed it. Perky claimedthat they had incorporated the slide into their mental image, and indeed,the subjects reported details in their image that could only have comefrom the slide, such as the banana's standing on end. It was not a greatexperiment by modern standards, but state-of-the-art methods haveborne out the crux of the finding, now called the Perky effect: holding amental image interferes with seeing faint and fine visual details.Imagery can affect perception in gross ways, too. When peopleanswer questions about shapes from memory, like counting off the rightangles in a block letter, their visual-motor coordination suffers. (Sincelearning about these experiments I try not to get too caught up in ahockey game on the radio while I am driving.) Mental images of lines canaffect perception just as real lines do: they make it easier to judge alignmentand can even induce visual illusions. When people see someshapes and imagine others, later they sometimes have trouble rememberingwhich was which.So do imagery and vision share space in the brain? The neuropsychologistsEdoardo Bisiach and Claudio Luzzatti studied two Milanesepatients with damage to their right parietal lobes that left them withvisual neglect syndrome. Their eyes register the whole visual field, butthey attend only to the right half: they ignore the cutlery to the left of theplate, draw a face with no left eye or nostril, and when describing aroom, ignore large details—like a piano—on their left. Bisiach and Luzzattiasked the patients to imagine standing in the Piazza del Duomo inMilan facing the cathedral and to name the buildings in the piazza. The