The Short Term Memory Structure In State-Of-The Art Recall/Recognition Experiments of Rubin, Hinton and Wentzel

Properties of a short term memory structure are discovered in the data of Rubin, Hinton and Wenzel (1999): Recall (recognition) probabilities and search times are linearly related through stimulus presentation lags from 6 seconds to 600 (350) seconds. This data suggest that only one memory structure is present in the Rubin, Hinton and Wenzel data. The data also suggest that the memory items have a finite effective size that shrinks to zero in a logarithmic fashion as the time since stimulus presentation increases, away from the start of the search. According to the logarithmic decay, the size of the memory items decreases to a couple of neurons at about 1200 seconds for recall and 350 seconds for recognition – this should be the time scale for a short term memory being converted to a long term memory. The incorrect recall time saturates, suggesting a limited size of the short term memory structure: the time to search through the structure for recall is 1.7 seconds. For recognition the corresponding time is about 0.4 seconds, a non-Sternberg experimental result to compare with the 0.243 seconds given by Cavanagh (1972)).