You read my mind: Generating and minimizing intention uncertainty under different social contexts in a two-player online game.

We investigate an ecologically pertinent form of social uncertainty regarding the ability to read another's intentions. We use classic measures (response time, accuracy) and dynamic measures (mouse trajectories) to investigate how people generate or minimize uncertainty regarding their own intentions under different social contexts, and how uncertainty regarding other's intentions affects decision making. Ninety-six participants (N = 48 dyads) completed a two-player online card game, where the goal was to collect cards with a certain feature (e.g., triangles), with participant cursor movements projected to both players. Participants played six games, three cooperatively and three competitively (Social Decision Context). Points were awarded for two decisions: collecting a card matching one's goal (ability to achieve personal goal) and correctly guessing the other player's goal (ability to guess intention). Data revealed: (a) Card scores did not vary with Social Decision Context, (b) Guess scores did vary with Social Decision Context, with more correct guesses when cooperating compared to competing, and (c) Mouse trajectories (durations and mouse distance traveled) decreased when cooperating compared to competing. These results indicate that better guessing during cooperative play is not due to explicit communication (i.e., circling desired cards), but may be due to increased speed and confidence when making decisions in a cooperative context. Additionally, participants could be actively hiding their intention in a competitive context. Thus, social uncertainty when reading another's intentions is both adaptive-affected by the prescribed social context, and automatic-indirectly inferred from the way another moves their mouse when acting with intention. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Reaching for known unknowns: Rapid reach decisions accurately reflect the future state of dynamic probabilistic information.

Everyday tasks such as catching a ball appear effortless, but in fact require complex interactions and tight temporal coordination between the brain's visual and motor systems. What makes such interceptive actions particularly impressive is the capacity of the brain to account for temporal delays in the central nervous system-a limitation that can be mitigated by making predictions about the environment as well as one's own actions. Here, we wanted to assess how well human participants can plan an upcoming movement based on a dynamic, predictable stimulus that is not the target of action. A central stationary or rotating stimulus determined the probability that each of two potential targets would be the eventual target of a rapid reach-to-touch movement. We examined the extent to which reach movement trajectories convey internal predictions about the future state of dynamic probabilistic information conveyed by the rotating stimulus. We show that movement trajectories reflect the target probabilities determined at movement onset, suggesting that humans rapidly and accurately integrate visuospatial predictions and estimates of their own reaction times to effectively guide action.

Clarifying frequency-dependent brightness enhancement: delta- and theta-band flicker, not alpha-band flicker, consistently seen as brightest.

Frequency-dependent brightness enhancement, a perceptual illusion in which a flickering light can appear twice as bright as a constant light, has historically been reported to produce maximum effects at a flicker rate within the alpha (8-12 Hz) band (Bartley in J Exp Psychol 23(3):313-319, 1938). Our recent examinations of this phenomenon using brightness discrimination between two flickering stimuli, however, have instead revealed the brightest percepts from theta-band (4-7 Hz) flicker (Bertrand et al. in Sci Rep 8(1):6152, 2018). Two primary questions arise from these seemingly contradictory findings: first, could task differences between these studies have caused recruitment of discrete oscillatory processes? Second, could the reported theta-band flicker enhancement be the result of an aliased alpha rhythm, sequentially sampling two stimulus locations, resulting in an ~ 5 Hz half-alpha rhythm? Here, we investigated these questions with two experiments: one replicating Bartley's (1938) adjustment paradigm, and one containing both Bartley's adjustment task and Bertrand's (2018) discrimination task, but presenting stimuli only sequentially (rather than concurrently). Examination of a range of frequencies (2-12 Hz) revealed the greatest brightness enhancement arising from flicker in the delta- and theta-band across all conditions, regardless of the spatial or temporal configuration of the stimuli. We speculate that these slower rhythms play an integral role in complex visual operations (e.g., a discrimination decision) where the entrainment of the endogenous neural rhythm to matched exogenous rhythmic stimulation promotes more efficient processing of visual information and thus produces perceptual biases as seen in frequency-dependent brightness enhancement.

Entrainment of theta, not alpha, oscillations is predictive of the brightness enhancement of a flickering stimulus.

Frequency-dependent brightness enhancement, where a flickering light can appear twice as bright as an equiluminant constant light, has been reported to exist within the alpha (8-12 Hz) band. Could oscillatory neural activity be driving this perceptual effect? Here, in two experiments, human subjects reported which of two flickering stimuli were brighter. Strikingly, 4 Hz stimuli were reported as brighter more than 80% of the time when compared to all other tested frequencies, even though all stimuli were equiluminant and of equal temporal length. Electroencephalography recordings showed that inter-trial phase coherence (ITC) of theta (4 Hz) was: (1) Significantly greater than alpha, contralateral to the flickering stimulus; (2) Enhanced by the presence of a second ipsilateral 4 Hz flickering stimulus; and (3) Uniquely lateralized, unlike the alpha band. Importantly, on trials with two identical stimuli (i.e. 4 Hz vs 4 Hz), the brightness discrimination judgment could be predicted by the hemispheric balance in the amount of 4 Hz ITC. We speculate that the theta rhythm plays a distinct information transfer role, where its ability to share information between hemispheres via entrainment promotes a better processing of visual information to inform a discrimination decision.