Confirming expectations in asymmetric and symmetric social hypothesis testing

This article examines individuals' expectations in a social hypothesis testing task. Participants selected questions from a list to investigate the presence of personality traits in a target individual. They also identified the responses that they expected to receive and the likelihood of the expected responses. The results of two studies indicated that when people asked questions inquiring about the hypothesized traits that did not entail strong a priori beliefs, they expected to find evidence confirming the hypothesis under investigation. These confirming expectations were more pronounced for symmetric questions, in which the diagnosticity and frequency of the expected evidence did not conflict. When the search for information was asymmetric, confirming expectations were diminished, likely as a consequence of either the rareness or low diagnosticity of the hypothesis-confirming outcome. We also discuss the implications of these findings for confirmation bias.     

A modular,computer-controlled system for olfactory stimulation in the MRI environment

Although the cerebral networks involved in sensory perception are of general interest in neuroscience, registration of the effects of olfactory stimulation, especially in a magnetic resonance imaging (MRI) environment, presents particular problems and constraints. This article presents details of a reliable and portable system for olfactory stimulation that is modular in design and based on microcontroller technology. It has the following characteristics: (1)?It is under software control; (2)?the presentation of olfactory stimulation can be synchronized with respiration; (3)?it can be manually controlled; and (4)?it is fully compatible with an MRI environment. The principle underlying this system is to direct an odor to the subject’s nostrils by switching airflow to different odor diffusers. The characteristics of this system were established using (1)?ultraviolet (UV) spectroscopy, to measure its response time, and (2)?gas chromatography, to measure the repeatability of odor presentation in terms of gas concentration. A response time of 200?± 25 ms was obtained for the system, and the standard deviations of the gas concentration delivered during stimulation ranged from 1.5% to 22%, depending on the odor, the airflow, and the dilution of the odor used. Since it is portable, controlled by software, and reliable, on the basis of the results we obtained, this system will lend itself to a wide range of applications in olfactory neuroscience.     

RITALIN UPDATE: IMPLICATIONS FOR READING TEACHERS

Ritalin (methylphenidate hydrochloride) is a powerful stimulant drug frequently prescribed for children exhibiting hyperactive behavior, poor attention span, and/or distractibility. Reading teachers and other educators have a particular interest in Ritalin since they frequently have students in their classes taking this medication. The researchers in this study were interested in determining how Ritalin is prescribed for children in educational settings, what dosages seem appropriate, and specifically, what effect Ritalin has on reading achievement. Implications for reading teachers are discussed.     

Integration of base rates and new information in an abstract hypothesis‐testing task

In two studies, we investigated how people use base rates and the presence versus the absence of new information to judge which of two hypotheses is more likely. Participants were given problems based on two decks of cards printed with 0–4 letters. A table showed the relative frequencies of the letters on the cards within each deck. Participants were told the letters that were printed on or absent from a card the experimenter had drawn. Base rates were conveyed by telling participants that the experimenter had chosen the deck by drawing from an urn containing, in different proportions, tickets marked either ‘deck 1’ or ‘deck 2’. The task was to judge from which of the two decks the card was most likely drawn. Prior probabilities and the evidential strength of the subset of present clues (computed as ‘weight of evidence’) were the only significant predictors of participants’ dichotomous (both studies) and continuous (Study 2) judgments. The evidential strength of all clues was not a significant predictor of participants’ judgments in either study, and no significant interactions emerged. We discuss the results as evidence for additive integration of base rates and the new present information in hypothesis testing.     

Estimating time to contact and impact velocity when catching an accelerating object with the hand

To catch a moving object with the hand requires precise coordination between visual information about the target's motion and the muscle activity necessary to prepare for the impact. A key question remains open as to if and how a human observer uses velocity and acceleration information when controlling muscles in anticipation of impact. Participants were asked to catch the moving end of a swinging counterweighted pendulum, and resulting muscle activities in the arm were measured. The authors also simulated muscle activities that would be produced according to different tuning strategies. By comparing data with simulations, the authors provide evidence that human observers use online information about velocity but not acceleration when preparing for impact.     

Inner speech sustains predictable task switching: direct evidence in adults

It has been proposed that inner speech supports task selection in task-switching studies, especially when the need for endogenous control is increased. This has been established through the suppression of inner speech in cognitive-flexibility tasks that leads to poorer performance. The aim of this study is to quantify the role of inner speech in a flexibility task by using surface laryngeal electromyography, which, contrary to previous studies, enables participants to freely verbalise the tasks. We manipulated endogenous and exogenous flexibility in a mathematical switching task paradigm. Experiment 1 shows that inner speech acts as a support for switching and is recruited more often when the tasks are of an endogenous type. The main result of Experiment 2 that language is recruited more for the mixing cost than for the switch cost (regardless of the endogenous factor) extends past findings obtained through articulatory suppression.     

Pharmacotherapy of aphasia: myth or reality?

Pharmacotherapy of aphasia had been discussed for the last twenty years with first bromocriptine and amphetamine and then serotoninergic, GABAergic and cholinergic agents. Here, we reviewed the MEDLINE available reports of drug therapy for aphasia. So far, proofs of efficiency were found indubitable for none of the studied molecules. However, some of them showed limited efficiency (piracetam and amphetamine). Moreover, drug therapies for aphasia were less efficient alone than when they were associated with speech therapy.     

Presence as determined by fractal perceptual-motor dynamics.

This paper presents a tentative model of the role of perceptual-motor dynamics in the emergence of the feeling of presence. A new method allowing the measure of how gaze probes three-dimensional space in immersion is used to support this model. Fractal computations of gaze behavior are shown to be more effective than standard computations of eye movements in predicting presence.