Working Memory Control in Patients With Schizophrenia: A PET Study During a Random Number Generation Task

Recent findings suggest that number processing is intimately linked to space and attention orienting processes. For example, processing numbers induces shifts of spatial attention, with small numbers causing leftward shifts and large numbers causing rightward shifts, suggesting that number magnitude might be represented on a left-to-right mental number line. However, whether inducing spatial attention shifts would in turn influence number production, and whether such influence, if observed, would be restricted to the left-to-right orientation or would extend to an up-to-down orientation in space, remains a matter of debate. The present study assessed whether observing gaze movements, known to moderate spatial attention, was able to influence a random number generation task, and how different directions of the gaze moderated this influence. Participants were asked to randomly produce a number between 1 and 10 after they observed either a horizontal or a vertical eye gaze, or after they observed color changes as a control condition. The results revealed that number production was influenced by the prior presentation of specific gaze changes. Observing leftward or downward gaze led participants to produce more small than large numbers, whereas observing gaze oriented rightward and upward or observing color changes did not influence the magnitude of the numbers produced. These results show that the characteristics of the observed gaze changes primed number magnitude, but that this only held true for some movements, and these were not restricted to the left-to-right axis.

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Stroop-Type Interference in Random-Number Generation

Psychological Reports ◽

10.2466/pr0.1995.77.2.387 ◽

1995 ◽

Vol 77 (2) ◽

pp. 387-390 ◽

Cited By ~ 10

Author(s):

Peter Brugger ◽

Sabine Pietzsch ◽

Gabriele Weidmann ◽

Peter Biro ◽

Eli Alon

Keyword(s):

Random Number ◽

Human Subjects ◽

Random Number Generation ◽

Naming Task ◽

Color Naming ◽

Generation Task ◽

Number Generation ◽

Psychological Theories ◽

Random Behavior ◽

Repetition Avoidance

We describe a positive correlation between the extent of sequential counting in a random-number generation task and the magnitude of the interference effect in Stroop's color-naming task. This finding is compatible with the view that both counting and reading are highly automatized processes which constitute an inevitable source of interference in randomization and Stroop paradigms, respectively. On the other hand, cognitive psychological theories proposing that a generally biased concept of randomness would be responsible for human subjects' inability to generate true random sequences do not readily account for this correlation. Literature on repetition avoidance indicates this universal effect in random generation is likewise not explainable in terms of some “biased concept of randomness.” Repetition avoidance (“spontaneous alternation”) also occurs in lower invertebrates, is largely independent of mathematical sophistication in humans, dissipates with increasing time between consecutive responses, and is diminished by amnesia. We conclude that the failure of functionally intact organisms to display random behavior is due to basic neuropsychological limitations. In neglecting these biological foundations, “concept of randomness” theories of randomization behavior lack explanatory value.

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Cognitive Processing dissociation by mental effort manipulation in long demanding tasks

10.1101/2020.04.25.060814 ◽

2020 ◽

Author(s):

Marcus Vinicius Alves ◽

Susanny Tassini ◽

Felipe Aedo-Jury ◽

Orlando F. A. Bueno

Keyword(s):

Cognitive Processing ◽

Random Number ◽

Random Number Generation ◽

High Sensitivity ◽

Mental Effort ◽

Experimental Manipulation ◽

Cognitive Resources ◽

Generation Task ◽

Non Invasive ◽

Number Generation

AbstractIndividuals uses cognitive resources to modulate performance in demanding tasks and a non-invasive and reliable way of measuring mental effort is pupillometry. This study aimed to test the mental effort related to different processing systems in long tasks with controlled and automatic demands. We conducted two experiments with healthy subjects: in Experiment 1 (n=15), using a metronome to ensure control on task pace, participants performed a serial number generation task (Counting; little to no effort tasks), a random number generation (RNG; effortful tasks), and no task (Unfilled interval; no effort at all). In experiment 2, (n=15) participants performed counting tasks with or without additional intermediary beeps produced by a metronome to assess the effect of a possible increase in effort demanded by the distractors. Experiment 1 showed differences between unfilled interval, counting and RNG. Experiment 2 showed that the intermediate beep made the counting tasks more demanding than the normal counting tasks. Notable in both experiments was the tendency of participants to demand mental effort at the beginning of the trial. These results indicate that previously effortless automatic tasks can become controlled, or at least more demanding, with a simple experimental manipulation. They also reveal that tasks that require mental effort over a long period will demand more than automatic ones, but even so the peak of this demand is in the initial trial period. Moreover, they reveal the high sensitivity of pupillometry for the measurement of mental effort employing different processing systems and cognitive resource modulation.

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