The influence of symbolic literacy on memory: testing Plato's hypothesis.

The present study examined the influence of the production of external symbols on memory strategies. Plato hypothesized that dependency on writing as an external memory store would be deterimental to memory. Three experiments were conducted to explore this hypothesis. Participants played Concentration, a memory game where players must find matching pairs of cards placed face down in an array. Participants were allowed to make notes to aid their performance under some experimental conditions, while under other conditions they could not. In Experiments 1 and 2, the unexpected removal of participants' notes revealed that the performance benefit was due to notes acting as a form of external memory storage, rather than as an aid to encoding information in memory. Experiment 3 qualified these findings by demonstrating that the identity of each card was retained in memory, while the location of each card tended to be stored in the participants' external notations. These data suggest a modified interpretation of Plato's hypothesis in that symbolic literacy may change how we remember information. Rather than storing all information in memory, we only have to retain the information necessary to use the much larger storage capacity of the external system. Thus, the introduction of external symbols allows for a change in how memory is adaptively distributed.

Children's use of triadic eye gaze information for "mind reading".

Five experiments examined children's use of eye gaze information for "mind-reading" purposes, specifically, for inferring another person's desire. When presented with static displays in the first 3 experiments, only by 4 years of age did children use another person's eye direction to infer desires, although younger children could identify the person's focus of attention. Further, 3-year-olds were capable of inferring desire from other nonverbal cues, such as pointing (Experiment 3). When eye gaze was presented dynamically with several other scaffolding cues (Experiment 4), 2- and 3-year-olds successfully used eye gaze for desire inference. Scaffolding cues were removed in Experiment 5, and 2- and 3-year-olds still performed above chance in using eye gaze. Results suggest that 2-year-olds are capable of using eye gaze alone to infer about another's desire. The authors propose that the acquisition of the ability to use attentional cues to infer another's mental state may involve both an association process and a differentiation process.