A value-driven McGurk effect: Value-associated faces enhance the influence of visual information on audiovisual speech perception and its eye movement pattern

Reward delays quitting in visual search

Reward motivates goal-directed behaviors, leading to faster reaction time (RT) and lower error rate in searching for a target in the reward condition than in the no-reward condition in target-discrimination tasks. However, it is unclear how reward influences target detection in which participants are required to judge whether a predesignated target is present or absent. Here, we asked participants to complete a target-detection search task in which the color of the search array indicated the reward availability of the current trial. Correct and faster (than a baseline) responses would be rewarded if the search array had the reward-related color. In Experiments 1A and 1B, the target was presented in 50% of the trials. Experiment 1B had the same design as Experiment 1A, except that different baselines were set for the target-present and target-absent conditions. In Experiment 2, the proportion of target presence was manipulated to be high (80%), moderate (50%), or low (20%) in different blocks of stimuli. Results showed that, across all the experiments, participants responded faster and made fewer errors in the reward than in the no-reward condition when the target was present. However, this facilitatory effect was reversed when the target was absent, showcasing a reward-induced interference. The signal detection analysis suggested that reward biased the report criterion to the "yes" response. These findings demonstrate that the impact of reward on goal-directed behavior can be detrimental and reward prolongs the search process by rendering participants reluctant to say "no" in visual search termination.

Reward reduces the fission illusion in the sound-induced flash illusion

Pairing a single visual stimulus with multiple auditory stimuli will lead to the illusory perception of multiple visual stimuli, which is known as sound-induced flash illusion (SIFI). The present study adopted the classic SIFI paradigm to investigate whether value-associated tasks could affect the SIFI. By adjusting the sequence of reward and nonreward conditions, we also examined the effect of reward history on SIFI. The results showed that the fission illusion was reduced when associated with momentary reward, demonstrating significantly higher accuracy and discriminability than the nonreward condition. However, the fusion illusion was not affected by the momentary reward, and the explanation was that the fusion illusion was not as stable as the fission illusion and disappeared across different trials and conditions. Moreover, the robustness of reward history in the present study was not as strong as previous studies have suggested, indicating that the effect of sound on the perceptual representation of visual stimuli is strong and robust to reward history. These findings demonstrated that the reward could reduce the SIFI and broaden the existing dichotomy of SIFI. New evidence for the operation of value-driven attention mechanisms is also provided, suggesting that the underlying value-driven attention operates across multiple sensory systems.

Belief in control: Voluntary choice enhances subsequent task performance under undefeated choice-outcome causation

Humans have volition through which they act upon and change the external environment. As an exercise of volition, making a voluntary choice facilitates subsequent behavioral performance relative to making a forced choice. However, it is unclear how this facilitation is constrained by the perceived relationship between a choice and its outcome. In a series of experiments, participants were free or forced to choose one of two presented pictures. The outcome of the choice was then revealed, which could be: always the chosen picture or always the unchosen picture (i.e., confirmed choice-outcome causation), a blank screen with no picture at all (i.e., unrevealed choice-outcome relation), the chosen or unchosen picture with equal probability (i.e., defeated choice-outcome causation), or a third picture different from the two preceding options (again, defeated choice-outcome causation). Participants then complete a visual search task with the task-irrelevant picture (or the blank screen) serving as a background. Results showed that search performance was improved after a voluntary choice under both confirmed causation and unrevealed relation, but not under defeated causation. Over individuals, the improved performance due to voluntary choice under confirmed causation positively correlated with the improved performance under unrevealed relation, and with reported belief in controlling the outcome of the choice. Our findings suggest that the exercise of volition motivates subsequent behavior, and this motivation is restricted to "undefeated" choice-outcome causation which affords a belief in controlling the outcome by exerting volition.