Biology subjects

Odegaard, B.

Publications and source records attributed to Odegaard, B..

6 recordsLinked to original sources

bioRxiv2018

Inflation versus filling-in: why we feel we see more than we actually do in peripheral vision

Do we perceive fine details in the visual periphery? Here, we propose that phenomenology in the visual periphery can be characterized by an inflated sense of perceptual capacity, as observers overestimate the quality of their perceptual inputs. Distinct from the well-known perceptual phenomenon of \"filling-in\" where perceptual content is generated or completed endogenously, inflation can be characterized by incorrect introspection at the subjective level. The perceptual content itself may be absent or weak (i.e., not necessarily filled-in), and yet such content is mistakenly regarded by the system as rich. Behaviorally, this can be reflected by metacognitive deficits in the degree to which confidence judgments track task accuracy, and decisional biases for observers to think particular items are present, even when they are not. In two experiments using paradigms which exploit unique attributes of peripheral vision (crowding and summary statistics), we provide evidence that both types of deficits are present in peripheral vision, as observers reports are marked by overconfidence in discrimination judgments and high numbers of false alarms in detection judgments. We discuss potential mechanisms which may be the cause of inflation and propose future experiments to further explore this unique sensory phenomenon.

animal behavior and cognition↗

bioRxiv2018

Liberal Detection Bias in the Unattended Periphery during Simulated Driving

While people often think they veridically perceive much of the visual surround, recent findings indicate that when asked to detect targets such as gratings embedded in visual noise, observers make more false alarms in the unattended periphery. Do these results from psychophysics studies generalize to naturalistic settings? We used a modern game engine to create a simulated driving environment where participants (as drivers) had to make judgments about the colors of pedestrians clothing in the periphery. Confirming our hypothesis based on previous psychophysics studies, we found that subjects showed liberal biases for unattended locations when detecting specific colors of pedestrians clothing. A second experiment showed that this finding was not simply due to a confirmation bias in decision-making when subjects were uncertain. Together, these results support the idea that in everyday visual experience, there is subjective inflation of experienced detail in the periphery, which may happen at the decisional level.

animal behavior and cognition↗

bioRxiv2017

Subjective inflation of color saturation in the periphery under temporal overload

A long-standing puzzle in perception concerns the subjective impression of vivid color experience in the periphery. While peripheral color processing is not entirely insensitive, the subjective vividness seems unsupported by the relative paucity of representation in the periphery. Inspired by the flashed face distortion effect, in which peripheral faces are perceived as somewhat exaggerated or distorted when they are preceded by flashes of other faces in the same location, we attempted to create an equivalent illusion in the domain of color. The hypothesis is that under temporal overload, patches of colorful dots may be perceived as more exaggerated in terms of saturation. We confirmed this hypothesis with the observation of a significant effect of modest magnitude, which was replicated in a second experiment. These results suggest that subjective inflation of perceived color saturation does occur in the periphery, when the perceptual system is sufficiently occupied temporally and spatially. We discuss the relationship between the observed effects with previous findings of liberal detection biases in the unattended periphery.

neuroscience↗

bioRxiv2017

A random dot kinematogram for online visual psychophysics

Web-{-}based experiments using visual stimuli have become increasingly common in recent years, but many frequently-used stimuli in vision research have yet to be developed for online platforms. Here, we introduce the first open access random-dot kinematogram (RDK) for use in web browsers. This fully customizable RDK offers options to implement several different types of noise (random position, random walk, random direction) and parameters to control aperture shape, coherence level, the number of dots, and other features. We include links to commented JavaScript code for easy implementation in web-based experiments, as well as an example of how this stimulus can be integrated as a plugin with a JavaScript library for online studies (jsPsych).

neuroscience↗

bioRxiv2017

Superior Colliculus Neuronal Ensemble Activity Signals Optimal Rather Than Subjective Confidence

Recent studies suggest that neurons in sensorimotor circuits involved in perceptual decision-making also play a role in decision confidence. In these studies, confidence is often considered to be an optimal readout of the probability that a decision is correct. However, the information leading to decision accuracy and the report of confidence often co-varied, leaving open the possibility that there are actually two dissociable signal types in the brain: signals that correlate with decision accuracy (optimal confidence) and signals that correlate with subjects behavioral reports of confidence (subjective confidence). We recorded neuronal activity from a sensorimotor decision area, the superior colliculus (SC) of monkeys, while they performed two different tasks. In our first task, decision accuracy and confidence co-varied, as in previous studies. In our second task, we implemented a novel motion discrimination task with stimuli that were matched for decision accuracy but produced different levels of confidence as reflected by behavioral reports. We used a multivariate decoder to predict monkeys choices from neuronal population activity. As in previous studies on perceptual decision-making mechanisms, we found that neuronal decoding performance increased as decision accuracy increased. However, when decision accuracy was matched, performance of the decoder was similar between high and low subjective confidence conditions. These results show that the SC likely signals optimal decision confidence similar to previously reported cortical mechanisms, but is unlikely to play a critical role in subjective confidence. The results also motivate future investigations to determine where in the brain signals related to subjective confidence reside.\n\nSignificance StatementConfidence is thought to reflect the rational or optimal belief concerning ones choice accuracy. Here, we introduce a novel version of the dot-motion discrimination task with stimulus conditions that produce similar accuracy but different subjective behavioral reports of confidence. We decoded decision performance of this task from neuronal signals in the superior colliculus (SC), a subcortical region involved in decision-making. We found that SC activity signaled a perceptual decision for visual stimuli, with the strength of this activity reflecting decision accuracy, but not the subjective level of confidence as reflected by behavioral reports. These results demonstrate an important role for the SC in perceptual decision-making and challenge current ideas about how to measure subjective confidence in monkeys and humans.

neuroscience↗

bioRxiv2017

Should A Few Null Findings Falsify Prefrontal Theories Of Conscious Perception?

Is activity in prefrontal cortex (PFC) critical for conscious perception? Major theories of consciousness make distinct predictions about the role of PFC, providing an opportunity to arbitrate between these views empirically. Here we address three common misconceptions: i) PFC lesions do not affect subjective perception; ii) PFC activity does not reflect specific perceptual content; iii) PFC involvement in studies of perceptual awareness is solely driven by the need to make reports required by the experimental tasks, rather than subjective experience per se. These claims are incompatible with empirical findings, unless one focuses only on studies using methods with limited sensitivity. The literature highlights PFCs essential role in enabling the subjective experience in perception, contra the objective capacity to perform visual tasks; conflating the two can also be a source of confusion.

neuroscience↗