Human Psychophysical Functions, an Update : Methods for Identifying their form; Estimating their Parameters; and Evaluating the Effects of Important Predictors

© The Psychometric Society 2014Stevens' power law for the judgments of sensation has a long history in psychology and is used in many psychophysical investigations of the effects of predictors such as group or condition. Stevens' formulation (Formula presented.), where (Formula presented.) is the psychological judgment, P is the physical intensity, and (Formula presented.) is the power law exponent, is usually tested by plotting log (Formula presented.) against log (P). In some, but by no means all, studies, effects on the scale parameter, (Formula presented.), are also investigated. This two-parameter model is simple but known to be flawed, for at least some modalities. Specifically, three-parameter functions that include a threshold parameter produce a better fit for many data sets. In addition, direct non-linear computation of power laws often fit better than regressions of log-transformed variables. However, such potentially flawed methods continue to be used because of assumptions that the approximations are "close enough" as to not to make any difference to the conclusions drawn (or possibly through ignorance the errors in these assumptions). We investigate two modalities in detail: duration and roughness. We show that a three-parameter power law is the best fitting of several plausible models. Comparison between this model and the prevalent two parameter version of Stevens' power law shows significant differences for the parameter estimates with at least medium effect sizes for duration.Peer reviewedFinal Accepted Versio

The association between the sense of control and depression during the COVID-19 pandemic: a systematic review and meta-analysis

© 2024 The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Introduction: High levels of depression and low sense of control have been reported during the COVID-19 pandemic. The removal of typical freedoms through public health restrictions may have played an important role. The aim of this review was to examine data collected during the pandemic and (1) estimate the strength of the association between sense of control and depression, (2) examine whether the different types of control measures affected the strength of the association, and (3) whether this changed as a function of pandemic indicators. Methods: We conducted a systematic review and meta-analysis of studies published in English between December 2019 and November 2022. A total of 993 articles were identified, of which 20 were included in the review and 16 in the meta-analysis after conducting a quality assessment using the standard NIH tool. Results: The control–depression association gave a bias-independent pooled effect size of r =.41, and grew stronger over the 130 weeks covered by this review but did not change as a function of local COVID incidence rates. Subgroup analyses showed that external and overall control were more strongly related to depression than internal control. Discussion: These findings emphasize that external factors are important to the sense of control and the importance of preserving the sense of control in situations where the removal of personal freedoms is necessary, such as public health emergencies.Peer reviewe

Using serum CA125 to assess the activity of potential cytostatic agents in ovarian cancer

Objective: New strategies are required to rapidly identify novel cytostatic agents before embarking on large randomized trials. This study investigates whether a change in rate of rise (slope) of serum CA125 from before to after starting a novel agent could be used to identify cytostatic agents. Tamoxifen was used to validate this hypothesis. Methods: Asymptomatic patients with relapsed ovarian cancer who had responded to chemotherapy were enrolled and had CA125 measurements taken every 4 weeks, then more frequently when rising. Once levels reached 4 times the upper limit of normal or nadir, they started continuous tamoxifen 20 mg daily, as well as fortnightly CA125 measurements until symptomatic progression. Because of the potentially nonlinear relationship of CA125 over time, it was felt that to enable normal approximations to be utilized a natural logarithmic standard transformation [ln(CA125)] was the most suitable to improve linearity above the common logarithmic transformation to base 10. Results: From 235 recruited patients, 81 started tamoxifen and had at least 4 CA125 measurements taken before and 4 CA125 measurements taken after starting tamoxifen, respectively. The mean regression slopes from using at least 4 1n(CA125) measurements immediately before and after starting tamoxifen were 0I0149 and 0I0093 [ln(CA125)/d], respectively. This difference is statistically significant, P = 0I001. Therefore, in a future trial with a novel agent, at least as effective as tamoxifen, using this effect size, the number of evaluable patients needed, at significance level of 5% and power of 80%, is 56. Conclusions: Further validation of this methodology is required, but there is potential to use comparison of mean regression slopes of ln(CA125) as an interim analysis measure of efficacy for novel cytostatic agents in relapsed ovarian cancer.Peer reviewedFinal Accepted Versio

Quality science from quality measurement: The role of measurement type with respect to replication and effect size magnitude in psychological research

Copyright: © 2018 Kornbrot et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.The quality of psychological studies is currently a major concern. The Many Labs Project (MLP) and the Open-Science-Collaboration (OSC) have collected key data on replicability and statistical effect sizes. We build on this work by investigating the role played by three measurement types: ratings, proportions and unbounded (measures without conceptual upper limits, e.g. time). Both replicability and effect sizes are dependent on the amount of variability due to extraneous factors. We predicted that the role of such extraneous factors might depend on measurement type, and would be greatest for ratings, intermediate for proportions and least for unbounded. Our results support this conjecture. OSC replication rates for unbounded, 43% and proportion 40% combined are reliably higher than those for ratings at 20% (effect size, w = .20). MLP replication rates for the original studies are: pro- portion = .74, ratings = .40 (effect size w = .33). Original effect sizes (Cohen’s d) are highest for: unbounded OSC cognitive = 1.45, OSC social = .90); next for proportions (OSC cogni- tive = 1.01, OSC social = .84, MLP = .82); and lowest for ratings (OSC social = .64, MLP = .31). These findings are of key importance to scientific methodology and design, even if the reasons for their occurrence are still at the level of conjecture.Peer reviewe

Impaired context maintenance in mild to moderately depressed students.

We test the hypothesis that people with depression experience difficulties in maintaining task-relevant context information over longer periods of time using the AX version of the continuous performance task (AX-CPT). The AX-CPT requires that participants maintain a context cue (A) in an active state in order to respond correctly to a target cue (X) presented after a short delay. A total of 40 nondepressed and mild to moderately depressed students completed versions of the task with short (1-s) or long (10-s) interstimulus intervals (ISIs). Mildly depressed participants made significantly more context-dependent (BX) errors, unlike controls who made more errors on trials where good context processing would impair performance (AY). This pattern of errors was only evident in the long ISI condition, suggesting poor maintenance of contextual informatio

Time perception and depressive realism: judgment type, psychophysical functions and bias

The effect of mild depression on time estimation and production was investigated. Participants made both magnitude estimation and magnitude production judgments for five time intervals (specified in seconds) from 3 sec to 65 sec. The parameters of the best fitting psychophysical function (power law exponent, intercept, and threshold) were determined individually for each participant in every condition. There were no significant effects of mood (high BDI, low BDI) or judgment (estimation, production) on the mean exponent, n = .98, 95% confidence interval (.96-1.04) or on the threshold. However, the intercept showed a 'depressive realism' effect, where high BDI participants had a smaller deviation from accuracy and a smaller difference between estimation and judgment than low BDI participants. Accuracy bias was assessed using three measures of accuracy: difference, defined as psychological time minus physical time, ratio, defined as psychological time divided by physical time, and a new logarithmic accuracy measure defined as In (ratio). The In (ratio) measure was shown to have approximately normal residuals when subjected to a mixed ANOVA with mood as a between groups explanatory factor and judgment and time category as repeated measures explanatory factors. The residuals of the other two accuracy measures flagrantly violated normality. The mixed ANOVAs of accuracy also showed a strong depressive realism effect, just like the intercepts of the psychophysical functions. There was also a strong negative correlation between estimation and production judgments. Taken together these findings support a clock model of time estimation, combined with additional cognitive mechanisms to account for the depressive realism effect. The findings also suggest strong methodological recommendations

The effect of mild depression on time discrimination.

Depressed mood states affect subjective perceptions of time but it is not clear whether this is due to changes in the underlying timing mechanisms, such as the speed of the internal clock. In order to study depression effects on time perception, two experiments using time discrimination methods with short (1000 ms) durations were conducted. Student participants who were categorised as mildly depressed by their scores on the Beck Depression Inventory were less able than controls to discriminate between two longer durations but were equally able to discriminate shorter intervals. The results suggest that mildly depressed or dysphoric mood do not affect pacemaker speed. It is more likely that depression affects the ability to maintain attention to elapsing duration

Summary statistics for replication rate proportion, pR.

<p>Summary statistics for replication rate proportion, pR.</p

DataSheet_1_The association between the sense of control and depression during the COVID-19 pandemic: a systematic review and meta-analysis.zip

IntroductionHigh levels of depression and low sense of control have been reported during the COVID-19 pandemic. The removal of typical freedoms through public health restrictions may have played an important role. The aim of this review was to examine data collected during the pandemic and (1) estimate the strength of the association between sense of control and depression, (2) examine whether the different types of control measures affected the strength of the association, and (3) whether this changed as a function of pandemic indicators.MethodsWe conducted a systematic review and meta-analysis of studies published in English between December 2019 and November 2022. A total of 993 articles were identified, of which 20 were included in the review and 16 in the meta-analysis after conducting a quality assessment using the standard NIH tool.ResultsThe control–depression association gave a bias-independent pooled effect size of r = .41, and grew stronger over the 130 weeks covered by this review but did not change as a function of local COVID incidence rates. Subgroup analyses showed that external and overall control were more strongly related to depression than internal control.DiscussionThese findings emphasize that external factors are important to the sense of control and the importance of preserving the sense of control in situations where the removal of personal freedoms is necessary, such as public health emergencies.</p