Why scientists valuep values

According to almost any approach to statistical inference, attained significance levels, orp values, have little value. Despite this consensus among statistical experts,p values are usually reported extensively in research articles in a manner that invites misinterpretation. In the present article, I suggest that the reasonp values are so heavily used is because they provide information concerning the strength of the evidence provided by the experiment. In some typical hypothesis testing situations, researchers may be interested in the relative adequacy of two different theoretical accounts: one that predicts no difference across conditions, and another that predicts some difference. The appropriate statistic for this kind of comparison is the likelihood ratio,P(D|M ₀)/P(D|M ₁), whereM ₀ andM ₁ are the two theoretical accounts. Large values of the likelihood ratio provide evidence thatM ₀ is a better account, whereas small values indicate thatM1 is better. I demonstrate that, under some circumstances, thep value can be interpreted in the same manner as the likelihood ratio. In particular, forZ,t, and sign tests, the likelihood ratio is an approximately linear function of thep value, with a slope between 2 and 3. Thus, researchers may reportp values in scientific communications because they are a proxy for the likelihood ratio and provide the readers with information about the strength of the evidence that is not otherwise available.     

Temporal integration and segregation of brief visual stimuli: Patterns of correlation in time

Two brief sequential displays separated by a brief interstimulus interval (ISI) are often perceived as a temporally integrated unitary configuration. The probability of temporal integration can be decreased by increasing the ISI or (counterintuitively) by increasing stimulus duration. We tested three hypotheses of the relative contributions of stimulus duration and ISI to the breakdown of temporal integration (the storage, processing, and temporal correlation hypotheses). In the first of two experiments, stimulus duration and ISI were varied factorially, and estimates of temporal integration were obtained with a form-part integration task. The second experiment was a replication of the first at two levels of stimulus intensity. The outcomes were inconsistent with the storage and processing options, but confirmed predictions from the temporal correlation hypothesis. Whether two sequential stimuli are perceived as temporally integrated or disjoint depends not on the availability of visible persistence, but on the emergence of a neural code that is based on the temporal correlation between the two visual responses.     

Numerical comparison processes

The relative lengths of two rows of objects systematically affected the time to make judgments of the relative number of objects. The time to decide which row contained more objects generally increased with the amount of incongruity between length and number (e.g., reaction time was long when the numerically larger row was the shorter of the two). In addition, the time to decide that the rows contained an equal number of objects increased with the disparity in length between the rows. These results suggest that length information was used in the numerical comparison process. A model that uses an internal transformation of row length is proposed to account for the results.     

Relationships between attentional blink magnitude, RSVP target accuracy, and performance on other cognitive tasks

When two masked, to-be-attended targets are presented within approximately half a second of each other, performance on the second target (T2) suffers, relative to when the targets are presented further apart in time or when the first target (T1) can be ignored. This pattern of results is known as the attentional blink (AB). Typically, participants differ with respect to the magnitude of their AB and their overall target accuracy. Despite investigations as to what participant characteristics may influence AB performance (e.g., age, brain damage, or mood state), there has been no focused examination of whether individual differences in cognitive performance measures predict the magnitude of the AB or overall rapid serial visual presentation(RSVP) target accuracy. Our university studentparticipants performed single-target and dual-target RSVP tasks, as well as a selection of cognitive tasks that did not use RSVP presentations, with color, letter, digit, and object stimuli. Overall performance on each of the RSVP targets (T1, T2, and single target) was predicted by speeded manual and vocal identification times to isolated stimuli and by performance with other RSVP targets. However, the magnitude of the AB was predicted only by T1 accuracy, not by any other performance measures. The results suggest that individual differences in AB magnitude do not result from differences in effective RSVP target encoding and are not well explained by varied information-processing abilities.     

Seeing big things: overestimation of heights is greater for real objects than for objects in pictures

In six experiments we demonstrate that the vertical-horizontal illusion that is evoked when viewing photographs and line drawings is relatively small, whereas the magnitude of this illusion when large objects are viewed is at least twice as great. Furthermore, we show that the illusion is due more to vertical overestimation than horizontal underestimation. The lack of a difference in vertical overestimation between pictures and line drawings suggests that vertical overestimation in pictures depends solely on the perceived physical size of the projection on the picture surface, rather than on what is apparent about an object's represented size. The vertical-horizontal illusion is influenced by perceived physical size. It is greater when viewing large objects than small pictures of these same objects, even when visual angles are equated.     

Performance variability is related to change in cognition: evidence from the Victoria Longitudinal Study

Performance variability across repeated task administrations may be an important indicator of age-related cognitive functioning. In the present investigation, the authors examined whether age differences and change in inconsistency were related to 6-year (3 occasion) cognitive change. Inconsistency scores were computed from 4 reaction time tasks performed by 446 older adults (54-89 years). Replicating previous cross-sectional results, greater inconsistency was observed for older participants even after controlling for differences in response speed. New longitudinal results demonstrated (a) associations between inconsistency at baseline measurement and 6-year change in cognitive performance; (b) longitudinal change in inconsistency; and (c) intraindividual covariation between 6-year change in inconsistency and 6-year change in level of cognitive function. These findings support the view that performance variability serves as a marker of cognitive aging.     

“I Can’t Operate,that Boy Is my Son!”: Gender Schemas and a Classic Riddle

Sex Roles - To study the power of lived experiences and conscious attitudes in helping individuals to overcome nonconscious gender schemas, U.S. university students (n?=?152) were...     

Teacher stress and burnout in Australia: examining the role of intrapersonal and environmental factors

Social Psychology of Education - Concerns regarding high rates of teacher stress and burnout are present globally. Yet there is limited current data regarding the severity of stress, or the role of...