Some Short-Term Memories Die Suddenly, No Fading

The human brain stores some kinds of memories for a lifetime. But when our eyes are open and looking at things, our gray matter also creates temporary memories that help us process complex tasks during the few seconds these visual memories exist. For decades, scientists have held that such short-term memories don’t suddenly disappear, but grow gradually more imprecise over the course of several seconds.  ScienceDaily (Apr. 30, 2009) 

According to the quote above, short-term memories gradually fade away. But researchers at the University of California have found that exactly the opposite happens. They did an experiment in which the participants had to retain temporary memories of an object’s colour or retain the shape of the object for four seconds. Afterwards, participants stated that the memories began to “wink out” and they were able to remember the shapes and colours accurately until at some point they suddenly disappeared.

                Another experiment done by Weiwei Chang and Steve Luck at UC Davis Center for mind and Brain. Their experiment consisted of asking 12 adult participants to answer a pair of tests which would separately measure the accuracy of a short-term memory and the probability that the memory still existed or went on to the long-term memory.  The first experiment consisted of flashing three different squares each filled with a different colour. They flashed the image for a tenth of a second  and in intervals of one, four or 10 seconds a wheel showing a spectrum of colours appeared. Afterwards, the three squares would reappear however, uncoloured,  and with one of the squares highlighted. Participants had to recall the colour of the highlighted square and clock the area of the spectrum that looked mostly like the colour they recalled. This process was carried out about 150 times for each of the three memory retention intervals. Results showed that when participants were able to retain a memory of colour they would click a colour very close to the one shown. The distance between the clock and the colour indicated the accuracy of memory. But when the participants were unable to recall the colour they would just click at a random part of the wheel.

                The second test carried out by Chang and Luck was similar to the first one, The only difference was that they used shapes instead of colours. The results were similar to the first one and Luck stated that the participants “either had the memory or did not have it” and the probability of having a memory decreased in a matter of four to ten seconds was very low. Therefore, memories do not gradually fade away. These findings help into the research of memory formation and retention and this would help in everyday life as it will prevent us from making decisions based on weak, inaccurate and unreliable memories.