Towards a visual recognition threshold: New instrument shows humans identify animals with only 1ms of visual exposure

Unconscious processing of subliminal stimuli in panic disorder: A systematic review and meta-analysis

Attentional biases to threat exist in panic disorder (PD), probably related to altered subliminal processing. We systematically reviewed studies investigating subliminal processing in PD. Studies were retrieved from MEDLINE and Scopus®. We meta-analytically compared PD (n = 167) and healthy controls (HC, n = 165) for processing of masked panic-related and neutral words. We also compared subliminal and supraliminal presentations of panic-related words relative to neutral words within PD subjects and HC. We found a significantly enhanced Stroop interference to masked panic-related words in PD vs HC (Hedges' g = 0.60, p = 0.03; Q = 14.83, I² = 66.3 %, p = 0.01). While both PD subjects and HC tended to be slower to respond to supraliminal threat words than to neutral words, PD subjects only showed a marginally significant slower response to subliminal panic-related words vs neutral words. Findings remain inconclusive regarding comparison to other mental disorders, neural correlates, and the effect of psychotherapy. Even if possibly flawed by methodological weaknesses, our findings support the existence of a sensitivity to subliminal threat cues in PD, which could be targeted to improve treatment.

A reminder on millisecond timing accuracy and potential replication failure in computer-based psychology experiments: An open letter

There is an ongoing 'replication crisis' across the field of psychology in which researchers, funders, and members of the public are questioning the results of some scientific studies and the validity of the data they are based upon. However, few have considered that a growing proportion of research in modern psychology is conducted using a computer. Could it simply be that the hardware and software, or experiment generator, being used to run the experiment itself be a cause of millisecond timing error and subsequent replication failure? This article serves as a reminder that millisecond timing accuracy in psychology studies remains an important issue and that care needs to be taken to ensure that studies can be replicated on current computer hardware and software.

Visual information representation and rapid-scene categorization are simultaneous across cortex: An MEG study

Perceiving the visual world around us requires the brain to represent the features of stimuli and to categorize the stimulus based on these features. Incorrect categorization can result either from errors in visual representation or from errors in processes that lead to categorical choice. To understand the temporal relationship between the neural signatures of such systematic errors, we recorded whole-scalp magnetoencephalography (MEG) data from human subjects performing a rapid-scene categorization task. We built scene category decoders based on (1) spatiotemporally resolved neural activity, (2) spatial envelope (SpEn) image features, and (3) behavioral responses. Using confusion matrices, we tracked how well the pattern of errors from neural decoders could be explained by SpEn decoders and behavioral errors, over time and across cortical areas. Across the visual cortex and the medial temporal lobe, we found that both SpEn and behavioral errors explained unique variance in the errors of neural decoders. Critically, these effects were nearly simultaneous, and most prominent between 100 and 250ms after stimulus onset. Thus, during rapid-scene categorization, neural processes that ultimately result in behavioral categorization are simultaneous and co-localized with neural processes underlying visual information representation.

The unsteady eye: an information-processing stage, not a bug

How is space represented in the visual system? At first glance, the answer to this fundamental question appears straightforward: spatial information is directly encoded in the locations of neurons within maps. This concept has long dominated visual neuroscience, leading to mainstream theories of how neurons encode information. However, an accumulation of evidence indicates that this purely spatial view is incomplete and that, even for static images, the representation is fundamentally spatiotemporal. The evidence for this new understanding centers on recent experimental findings concerning the functional role of fixational eye movements, the tiny movements humans and other species continually perform, even when attending to a single point. We review some of these findings and discuss their functional implications.

Could millisecond timing errors in commonly used equipment be a cause of replication failure in some neuroscience studies?

Neuroscience is a rapidly expanding field in which complex studies and equipment setups are the norm. Often these push boundaries in terms of what technology can offer, and increasingly they make use of a wide range of stimulus materials and interconnected equipment (e.g., magnetic resonance imaging, electroencephalography, magnetoencephalography, eyetrackers, biofeedback, etc.). The software that bonds the various constituent parts together itself allows for ever more elaborate investigations to be carried out with apparent ease. However, research over the last decade has suggested a growing, yet underacknowledged, problem with obtaining millisecond-accurate timing in some computer-based studies. Crucially, timing inaccuracies can affect not just response time measurements, but also stimulus presentation and the synchronization between equipment. This is not a new problem, but rather one that researchers may have assumed had been solved with the advent of faster computers, state-of-the-art equipment, and more advanced software. In this article, we highlight the potential sources of error, their causes, and their likely impact on replication. Unfortunately, in many applications, inaccurate timing is not easily resolved by utilizing ever-faster computers, newer equipment, or post-hoc statistical manipulation. To ensure consistency across the field, we advocate that researchers self-validate the timing accuracy of their own equipment whilst running the actual paradigm in situ.

Shapes displayed with durations in the microsecond range do not obey Bloch's law of temporal summation

Shape patterns were displayed with simultaneous brief flashes from a light-emitting diode array. Flash durations in the microsecond range and luminous intensities were adjusted to vary the degree of successful shape recognition. Four experiments were conducted to test whether Bloch's law would apply in this task. Bloch's law holds that for very brief flashes the perceptual threshold is determined by the total number of photons being delivered, i.e., there is reciprocity of intensity and duration. The present results did not find that effectiveness of flashes was based on the total quantity of photons, as predicted by Bloch's law. Additionally, the evidence points to a visual mechanism that has ultra-high temporal precision that either registers the rate of photon flux or the duration of flashes.