Adaptive Efficient Coding: A Variational Auto-encoder Approach

We study a model of neural coding with the structure of a variational auto-encoder. The model posits that the encoding of individual stimulus values is optimally adjusted for a finite training sample of stimuli retained in memory. We demonstrate that this model can rationalize existing experimental evidence on both perceptual discrimination thresholds and neural tuning curve widths in multiple sensory domains. Finally, since our model implies that encoding is optimized for a sample from the environment, it also provides predictions about the adaptation of neural coding as the environmental frequency distribution changes.

Cue competition influences biconditional discrimination

When multiple cues are presented in compound and trained to predict an outcome, the cues may compete for association with an outcome. However, if both cues are necessary for solution of the discrimination, then competition might be expected to interfere with the solution of the discrimination. We consider how unequal stimulus salience influences learning in configural discriminations, where no individual stimulus predicts the outcome. We compared two hypotheses: (1) salience modulation minimises the initial imbalance in salience and (2) unequal stimulus salience will impair acquisition of configural discriminations. We assessed the effect of varying stimulus salience in a biconditional discrimination (AX+, AY−, BX−, BY+). Across two experiments, we found stronger discrimination when stimuli had matched, rather than mismatched, salience, supporting our second hypothesis. We discuss the implications of this finding for Mackintosh’s model of selective attention, modified elemental models and configural models of learning.

Crossmodal correspondences

For more than a century now, researchers have acknowledged the existence of crossmodal congruency effects between dimensions of sensory stimuli in the general (i.e., non-synesthetic) population. Such phenomena, known by a variety of terms including ‘crossmodal correspondences’, involve individual stimulus properties, rely on a crossmodal mapping of unisensory features, and appear to be shared by the majority of individuals. Over the last few years, a number of studies have shed light on many key aspects of crossmodal correspondences, ranging from their role in multisensory integration, their developmental trajectories, their occurrence in non-human mammals, their neural underpinning and the role of learning. I will present a brief overview of the latest findings on crossmodal correspondences, highlight standing questions and provide direction for future research.

Effect of Color Schemes and Environmental Sensitivity on Job Satisfaction and Perceived Performance

Effects of interior office color and individual stimulus screening ability, i.e., instinctive perceptual filtering of irrelevant stimuli, on perceived performance and job satisfaction were examined on various outcome measures over a 4-day work week in a laboratory setting. Workers performed specific tasks and worked regular hours for 4 consecutive days in the same office. They were separated into three groups according to their ability to ignore irrelevant stimuli in the interior space. Those in the white and predominantly blue-green offices reported higher perceived job performance and satisfaction than those in the predominantly red office regardless of stimulus screening ability. Workers with high to moderate stimulus screening ability indicated greater perceived performance and job satisfaction than did workers with low stimulus screening ability. Results for color schemes are discussed in terms of preference and social expectations.