To better understand the sources of visual working memory limitations we explore the possibility that its capacity is limited by two systems: a representational system that enables formation of independent representations of visual objects, and an active maintenance system that enables sustained activation of the established representations in the absence of external stimuli. A total of 392 participants took part in four experiments in which they were asked to maintain orientation of items presented to the left, right or both visual hemifields. In all four experiments participants were able to maintain more items when they were distributed across both versus one visual hemifield, consistent with the proposal that bilateral display enables utilization of representational capacities of both hemispheres. Bilateral capacity, however, did not reach the combined representational potential of both hemispheres, indicating that the capacity is further limited by a second, unitary active maintenance system. Our study further suggests that both systems' capacities change throughout the lifespan very similarly. They both increase through development, reach a peak at the same age and decrease in healthy aging. This indicates that systems beyond executive processes, which receive most attention in the literature, are contributing to the decline in working memory in healthy aging.
COBISS.SI-ID: 71052130
Reward processing and cognition are disrupted in schizophrenia (SCZ), yet how these processes interface is unknown. In SCZ, deficits in reward representation may affect motivated, goal-directed behaviors. To test this, we examined the effects of monetary reward on spatial working memory (WM) performance in patients with SCZ. To capture complimentary effects, we tested biophysically grounded computational models of neuropharmacologic manipulations onto a canonical fronto-parietal association cortical microcircuit capable of WM computations. Patients with SCZ (n = 33) and healthy control subjects (HCS; n = 32) performed a spatial WM task with 2 reward manipulations: reward cues presented prior to each trial, or contextually prior to a block of trials. WM performance was compared with cortical circuit models of WM subjected to feed-forward glutamatergic excitation, feed-forward GABAergic inhibition, or recurrent modulation strengthening local connections. Results demonstrated that both groups improved WM performance to reward cues presented prior to each trial (HCS d = - 0.62; SCZ d = 1.0), with percent improvement correlating with baseline WM performance (r = .472, p ( .001). However, rewards presented contextually before a block of trials did not improve WM performance in patients with SCZ (d = 0.01). Modeling simulations achieved improved WM precision through strengthened local connections via neuromodulation, or feed-forward inhibition. Taken together, this work...
COBISS.SI-ID: 68508002
Research in psychology generates complex data and often requires unique statistical analyses. These tasks are often very speci?c, so appropriate statistical models and methods cannot be found in accessible Bayesian tools. As a result, the use of Bayesian methods is limited to researchers and students that have the technical and statistical fundamentals that are required for probabilistic programming. Such knowledge is not part of the typical psychology curriculum and is a dif?cult obstacle for psychology students and researchers to overcome. The goal of the bayes4psy package is to bridge this gap and offer a collection of models and methods to be used for analysing data that arises from psychological experiments and as a teaching tool for Bayesian statistics in psychology. The package contains the Bayesian t-test and bootstrapping along with models for analysing reaction times, success rates, and tasks utilizing colors as a response. It also provides the diagnostic, analytic and visualization tools for the modern Bayesian data analysis work?ow.
COBISS.SI-ID: 14800387