75 research outputs found
Beyond the Vestibulo-Ocular Reflex:Vestibular Input is Processed Centrally to Achieve Visual Stability
The current study presents a re-analysis of data from Zink et al. (1998, Electroencephalography and Clinical Neurophysiology, 107), who administered galvanic vestibular stimulation through unipolar direct current. They placed electrodes on each mastoid and applied either right or left anodal stimulation. Ocular torsion and visual tilt were measured under different stimulation intensities. New modelling introduced here demonstrates that directly proportional linear models fit reasonably well with the relationship between vestibular input and visual tilt, but not to that between vestibular input and ocular torsion. Instead, an exponential model characterised by a decreasing slope and an asymptote fitted best. These results demonstrate that in the results presented by Zink et al. (1998), ocular torsion could not completely account for visual tilt. This suggests that vestibular input is processed centrally to stabilise vision when ocular torsion is insufficient. Potential mechanisms and seemingly conflicting literature are discussed
Tutorial: a priori estimation of sample size, effect size, and statistical power for cluster analysis, latent class analysis, and multivariate mixture models
Before embarking on data collection, researchers typically compute how many
individual observations they should do. This is vital for doing studies with
sufficient statistical power, and often a cornerstone in study
pre-registrations and grant applications. For traditional statistical tests,
one would typically determine an acceptable level of statistical power,
(gu)estimate effect size, and then use both values to compute the required
sample size. However, for analyses that identify subgroups, statistical power
is harder to establish. Once sample size reaches a sufficient threshold, effect
size is primarily determined by the number of measured features and the
underlying subgroup separation. As a consequence, a priory computations of
statistical power are notoriously complex. In this tutorial, I will provide a
roadmap to determining sample size and effect size for analyses that identify
subgroups. First, I introduce a procedure that allows researchers to formalise
their expectations about effect sizes in their domain of choice, and use this
to compute the minimally required number of measured variables. Next, I outline
how to establish the minimum sample size in subgroup analyses. Finally, I use
simulations to provide a reference table for the most popular subgroup
analyses: k-means, Ward agglomerative hierarchical clustering, c-means fuzzy
clustering, latent class analysis, latent profile analysis, and Gaussian
mixture modelling. The table shows the minimum numbers of observations per
expected subgroup (sample size) and features (measured variables) to achieve
acceptable statistical power, and can be readily used in study design.Comment: Code and data: https://github.com/esdalmaijer/cluster_power_tutoria
Cumulative culture spontaneously emerges in artificial navigators who are social and memory-guided
Cumulative cultural evolution occurs when adaptive innovations are passed
down to consecutive generations through social learning. This process has
shaped human technological innovation, but also occurs in non-human species.
While it is traditionally argued that cumulative culture relies on
high-fidelity social transmission and advanced cognitive skills, here I show
that a much simpler system suffices. Cumulative culture spontaneously emerged
in artificial agents who navigate with a minimal cognitive architecture of
goal-direction, social proximity, and route memory. Within each generation,
naive individuals benefitted from being paired with experienced navigators
because they could follow previously established routes. Crucially, experienced
navigators also benefitted from the presence of naive individuals through
regression to the goal. As experienced agents followed their memorised path,
their naive counterparts (unhindered by route memory) were more likely to err
towards than away from the goal, and thus biased the pair in that direction.
This improved route efficiency within each generation. In control experiments,
cumulative culture was attenuated when agents' social proximity or route memory
were lesioned, whereas eliminating goal-direction only reduced efficiency.
These results demonstrate that cumulative cultural evolution occurs even in the
absence of sophisticated communication or thought. One interpretation of this
finding is that current definitions are too loose, and should be narrowed. An
alternative conclusion is that rudimentary cumulative culture is an emergent
property of systems that seek social proximity and have an imprecise memory
capacity, providing a flexible complement to traditional evolutionary
mechanisms.Comment: Code: https://github.com/esdalmaijer/artificial_navigators Data:
https://doi.org/10.5281/zenodo.694418
The Graded Fate of Unattended Stimulus Representations in Visuospatial Working Memory.
As in visual perception, information can be selected for prioritized processing at the expense of unattended representations in visual working memory (VWM). However, what is not clear is whether and how this prioritization degrades the unattended representations. We addressed two hypotheses. First, the representational quality of unattended items could be degraded as a function of the spatial distance to attended information in VWM. Second, the strength with which an item is bound to its location is degraded as a function of the spatial distance to attended information in VWM. To disentangle these possibilities, we designed an experiment in which participants performed a continuous production task in which they memorized a visual array with colored discs, one of which was spatially retro-cued, informing the target location of an impending probe that was to be recalled (Experiment 1). We systematically varied the spatial distance between the cued and probed locations and obtained model-based estimates of the representational quality and binding strengths at varying cue-probe distances. Although the representational quality of the unattended representations remained unaffected by the cue-probe distance, spatially graded binding strengths were observed, as reflected in more spatial confusions at smaller cue-probe distances. These graded binding strengths were further replicated with a model-free approach in a categorical version of the production task in which stimuli and responses consisted of easily discriminable colors (Experiment 2). These results demonstrate that unattended representations are prone to spatial confusions due to spatial degradation of binding strengths in WM, even though they are stored with the same representational quality
Banana for scale:Gauging trends in academic interest by normalising publication rates to common and innocuous keywords
Banana for scale: Gauging trends in academic interest by normalising publication rates to common and innocuous keywords
Many academics use yearly publication numbers to quantify academic interest
for their research topic. While such visualisations are ubiquitous in grant
applications, manuscript introductions, and review articles, they fail to
account for the rapid growth in scientific publications. As a result, any
search term will likely show an increase in supposed "academic interest". One
proposed solution is to normalise yearly publication rates by field size, but
this is arduous and difficult. Here, we propose an simpler index that
normalises keywords of interest by a ubiquitous and innocuous keyword, such as
"banana". Alternatively, one could opt for field-specific keywords or
hierarchical structures (e.g. PubMed's Medical Subject Headings, MeSH) to
compute "interest market share". Using this approach, we uncovered plausible
trends in academic interest in examples from the medical literature. In
neuroimaging, we found that not the supplementary motor area (as was previously
claimed), but the prefrontal cortex is the most interesting part of the brain.
In cancer research, we found a contemporary preference for cancers with high
prevalence and clinical severity, and notable declines in interest for more
treatable or likely benign neoplasms. Finally, we found that interest in
respiratory viral infections spiked when strains showed potential for pandemic
involvement, with SARS-CoV-2 and the COVID-19 pandemic being the most extreme
example. In sum, the time is ripe for a quick and easy method to quantify
trends in academic interest for anecdotal purposes. We provide such a method,
along with software for researchers looking to implement it in their own
writing.Comment: The software described in this manuscript can be found on
https://github.com/esdalmaijer/bibliobanan
Forever yuck: Oculomotor avoidance of disgusting stimuli resists habituation.
Disgust is an adaptation forged under the selective pressure of pathogens. Yet disgust may cause problems in contemporary societies because of its propensity for "false positives" and resistance to corrective information. Here, we investigate whether disgust, as revealed by oculomotor avoidance, might be reduced through the noncognitive process of habituation. In each of three experiments, we repeatedly exposed participants to the same pair of images, one disgusting and one neutral, and recorded gaze. Experiment 1 (N = 104) found no decline in oculomotor avoidance of the disgusting image after 24 prolonged exposures. Experiment 2 (N = 99) replicated this effect and demonstrated its uniqueness to disgust. In Experiment 3 (N = 93), we provided a gaze-contingent reward to ensure perceptual contact with the disgusting image. Participants looked almost exclusively at the disgusting image for 5 min but resumed baseline levels of oculomotor avoidance once the reward ceased. These findings underscore the challenge of reducing disgust. (PsycInfo Database Record (c) 2021 APA, all rights reserved)
П.А. Столыпин и развитие сельской кредитной кооперации в дореволюционной России
Цель статьи - рассмотрение аграрной реформы П.А. Столыпина в контексте развития в дореволюционной России сельской кредитной кооперации
Effects of task and task-switching on temporal inhibition of return, facilitation of return, and saccadic momentum during scene viewing
During scene viewing, saccades directed toward a recently fixated location tend to be delayed relative to saccades in other directions (“delay effect”), an effect attributable to inhibition-of-return (IOR) and/or saccadic momentum (SM). Previous work indicates this effect may be task-specific, suggesting that gaze control parameters are task-relevant and potentially affected by task-switching. Accordingly, the present study investigated task-set control of gaze behavior using the delay effect as a measure of task performance. The delay effect was measured as the effect of relative saccade direction on preceding fixation duration. Participants were cued on each trial to perform either a search, memory, or rating task. Tasks were performed either in pure-task or mixed-task blocks. This design allowed separation of switch-cost and mixing-cost. The critical result was that expression of the delay effect at 2-back locations was reversed on switch versus repeat trials such that return was delayed in repeat trials but speeded in switch trials. This difference between repeat and switch trials suggests that gaze-relevant parameters may be represented and switched as part of a task-set. Existing and new tests for dissociating IOR and SM accounts of the delay effect converged on the conclusion that the delay at 2-back locations was due to SM, and that task-switching affects SM. Additionally, the new test simultaneously replicated non-corroborating results in the literature regarding facilitation-of-return (FOR), which confirmed its existence and showed that FOR is “reversed” SM that occurs when preceding and current saccades are both directed toward the 2-back location
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