George Spelling’s Experiment It was in the 1960s

George Spelling’s Experiment It was in the 1960s that the existence of iconic memory was proven with the help of a series of experiments conducted by an American psychologist named George Spelling. In the experiment, the subjects were asked to recall a set of 9 letters (three letters each in three rows). The letters were projected on to a screen for a brief period (one-twentieth of a second) with the help of a tachistoscope. It was observed that most participants were able to recall four or five letters. According to Spelling, the participants were unable to recall all the letters even when all of them had been registered, as the memory had faded too quickly. Another Experiment In another experiment, a set of twelve letters was projected on to the screen, but a tone was sounded right after the letters were flashed. The subjects were given the instructions to recite only the letters in the top, middle, and bottom row on hearing the high, medium, and low tone respectively. It was observed that the participants had no difficulty in recalling the letters in the row indicated by the tone. On an average, most subjects were able to recall 3 out of 4 letters in the row. This proved that all the twelve letters had been registered in the visual sensory store. Experiment by Guttmann and Jules (1963) in 1963, Guttmann and Jules asked the participants to put on headphones and listen to the repeated segments of white noise (noise produced by a stimulus that contains all the audible frequencies of vibration) produced with the help of a computer. It was ensured that a repeating pattern of white noise was put together without any gap between repetitions.