The effects of total sleep deprivation on the generation of random sequences of key-presses, numbers and nouns

According to a recent hypothesis, executive functions should be particularly vulnerable to the effects of total sleep deprivation. Random generation is a task that taps executive functions. In three experiments we examined the effects of total sleep deprivation on random generation of keypresses, numbers, and nouns, in particular on the suppression of prepotent responses and the selection of next responses by way of applying a local-representativeness heuristic. With random key-presses suppression of prepotent responses did not suffer from lack of sleep, but it became poorer at a sufficiently high pacing rate. In contrast, suppression of prepotent responses suffered when numbers and nouns were generated. According to these findings different types of random generation tasks involve different types of inhibitory process. With only four response alternatives, but not with larger response sets, application of the local-representativeness heuristic was impaired after a night without sleep. In terms of a simple formal model, serial-order representations of the preceding responses are used in selecting the next response only for the small response set, and not for larger response sets. Thus, serial-order representations are likely to suffer from loss of sleep. These findings strongly suggest that random generation involves multiple processes and that total sleep deprivation does not impair all sorts of executive functions, but only some.     

Gesture offers insight into problem‐solving in adults and children

When asked to explain their solutions to a problem, both adults and children gesture as they talk. These gestures at times convey information that is not conveyed in speech and thus reveal thoughts that are distinct from those revealed in speech. In this study, we use the classic Tower of Hanoi puzzle to validate the claim that gesture and speech taken together can reflect the activation of two cognitive strategies within a single response. The Tower of Hanoi is a well‐studied puzzle, known to be most efficiently solved by activating subroutines at theoretically defined choice points. When asked to explain how they solved the Tower of Hanoi puzzle, both adults and children produced significantly more gesture‐speech mismatches—explanations in which speech conveyed one path and gesture another—at these theoretically defined choice points than they produced at non‐choice points. Even when the participants did not solve the problem efficiently, gesture could be used to indicate where the participants were deciding between alternative paths. Gesture can, thus, serve as a useful adjunct to speech when attempting to discover cognitive processes in problem‐solving.