Tracking priors and their replacement: Mental dynamics of decision making in the number-line task

Several theories of decision making assume that optimal decisions are reached by computing a prior distribution over possible responses, and then updating it according to the evidence received. We show how this prior replacement, with its two processing stages, can be captured with a simple behavioral method: tracking the finger movement as participants point to a response location. On each trial, participants saw a number and pointed to its location on a number line. In two experiments we manipulated either the prior, via the distribution of target numbers, or the initial finger direction, via explicit instruction. In both experiments, when a trial started the participants pointed toward the instructed direction, and in the last part of the trial they pointed toward the target. Critically, between these two stages there was a third, interim stage in which the participants pointed toward the prior before deviating toward the target. Transient pointing toward the prior was observed even when it induced a brief deviation away from the target. This pattern fits a model wherein decisions are first driven by prior knowledge, followed by the accumulation of trial-specific evidence.

Effects of syllable name change on pitch comparison

Previous research has found that musicians’ pitch judgments, unlike non-musicians’, are influenced by syllable names. Although non-musicians fail to identify absolute pitches, they acknowledge the direction of pitch change. The present experiment investigated whether non-musicians’ judgments of pitch change can be influenced by the direction of syllable name change. Moreover, we examined the spatial, magnitudinal and sequential nature of pitches and syllable names. Participants (N = 33) were asked to hear two successive tones sung by syllable name and to judge the direction of pitch change by pressing vertically arranged buttons. Participants’ accuracy of pitch change judging was found to be influenced by the direction of syllable name change. However, the response location was not found to interact with pitch change or syllable name change. The distance effect was found in pitches but not in syllable names. A sequence effect was found that trials with early-in-sequence syllable names were responded faster than trials with late-in-sequence syllable names. These results suggest that syllable names can influence non-musicians’ pitch judgments in a relative context. We suggest that it is the sequential order of syllable names that is the product of cultural activities that interfere with the judgment of pitch change.

More Than Hitting the Correct Key Quickly

Many studies have documented that multitasking reduces Response Time (RT) indicators of implicit sequence learning as well as the expression of acquired sequence knowledge in RT benefits. In these tasks it is only relevant that the correct key is hit quickly, not where it is hit. We explored how variability in response location is influenced by (a) breaking a repeating sequence of target locations, (b) multitasking demands in the current trial, and (c) presence of multitasking in the block. Participants performed a Serial Reaction Time Task (SRTT) on a touchscreen while shutting down a beep tone by pressing the space bar with their non-dominant hand (throughout Experiment 1 and in the second half of Experiment 2). The first-order sequence of four response locations on the screen was broken by off-sequence deviants in 1/6th of the trials. Our results show a dissociation between RT and response location variability. While the effect of breaking the sequence on RT was larger under single- than under multitasking, breaking the sequence only led to an increase in response location variability under multitasking. Experiment 3 suggested that the impact of sequence knowledge on either aspect of performance in the SRTT is limited by interference from an additional task.

Irrelevant Location Information Influences Accuracy in Bowling

Most cognitive control effects, although numerously reported in computer task studies, have rarely been tested outside the laboratory. The purpose of this study was twofold. First, we aimed to improve the ecological validity of a well-studied congruency effect. The Simon effect (Simon, 1969) is the observation that an irrelevant stimulus location can facilitate or impede task performance when it is congruent or incongruent with the response location. Secondly, we wanted to investigate the role of action experience on the Simon effect. In this study, experienced bowlers were asked to hit either the left- or rightmost pin, depending on the pitch of a tone. Irrelevant to the task, this tone could be presented in the congruent or incongruent ear. Our results demonstrate that the Simon effect can be observed outside the laboratory and that weekly training at bowling may help in shielding against irrelevant location stimuli.