After more than 230 hours of practice in the laboratory, a subject was able to increase his memory span from 7 to 79 digits. His performance on other memory tests with digits equaled that of memory experts with lifelong training. With an appropriate mnemonic system, there is seemingly no limit to memory performance with practice.

This paper develops a technique for isolating and studying the perceptual structures that chess players perceive. Three chess players of varying strength — from master to novice — were confronted with two tasks: (1) A perception task, where the player reproduces a chess position in plain view, and (2) de Groot's (1965) short-term recall task, where the player reproduces a chess position after viewing it for 5 sec. The successive glances at the position in the perceptual task and long pauses in the memory task were used to segment the structures in the reconstruction protocol. The size and nature of these structures were then analyzed as a function of chess skill.

The present study outlines a theory of how people compare sentences against pictures. This theory was tested in four experiments in which Ss were timed as they judged whether a sentence (e.g., Star isn't above plus) was true or false of a picture (e.g., +∗). The latencies in these tasks were consistent with the thesis that: (1) sentences are represented in terms of elementary propositions; (2) pictures are encoded in the same interpretive format; (3) these two codes are compared in an algorithmic series of mental operations, each of which contributes additively to the response latency; and (4) sentence encoding, picture encoding, comparing, and responding are four serially ordered stages, and their component latencies are additive. From these results, it was also possible to rule out certain explanations based on visual imagery, conversion (e.g., converting isn't above into is below), reading time, normative word frequencies, and other factors. Finally, it was shown that this theory is consistent with previous studies on sentence comprehension, sentence verification, concept verification, and other related phenomena.

Seymour has shown recently that people take less time to judge that the word above correctly describes the spatial position of a small circle drawn above a large reference square than they do for the word below and the circle below the square. Seymour has attributed this asymmetry to the tendency for people to invariably scan a picture from top to bottom. In the present study, the first experiment confirms Seymour's results, but the next three demonstrate that the asymmetry Seymour found cannot be accounted for by an attentional‐scanning process. Instead, it is proposed that people interpret the words above and below as abstract symbols at a first stage of processing, interpret the pictures above and below as abstract symbols at an independent second stage, and compare these two sets of symbols at an independent third stage. In support of this model, the results show, for example, that above is interpreted about 80 msec. faster than below at the first stage quite independently of what happens at the second and third stages. The asymmetry Seymour found is therefore attributable to the difference in the interpretation times of above and below at the first stage of processing.