Contrary to the widespread belief that careful conscious thought leads to good decisions, recent psychophysical studies have argued that unconscious information can improve conscious decisions. However, these studies likely failed to manipulate conscious awareness in their experiments. To address this issue, we used a new technique called continuous flash suppression (CFS), which provides a powerful method to reliably manipulate conscious awareness in visual perception. This technique was combined with a simple perceptual decision paradigm in the same experimental protocol as the recent psychophysical studies. This protocol enabled us to investigate whether unconscious information can alter conscious perceptual decisions. Participants were asked to decide the direction of a coherent random-dot motion stimulus and then to rate the confidence of the random-dot motion direction judgments. We found that unconscious motion information was not integrated with conscious decision-related motion information to increase both decision accuracy and confidence when the motion stimuli were presented for the first few hundred milliseconds with strong perceptual suppression induced by the CFS stimuli. These results suggest that unconscious information does not improve conscious decisions.

This study investigates the influence of visual cognitive processing on coordinated eye and head movements, aiming to elucidate the intricate relationship between eye-head coordination and visual cognitive processes. Through reanalysis of behavioral data from three visual cognitive tasks from previous studies, the results reveal that these movements involve a combination of multiple saccades and fixations. Notably, during fixations, the head orientation effect increases with visual field size, while during saccades, the head contribution also rises with visual field size. Additionally, head contribution escalates with the number of saccades within a single head movement. The interdisciplinary review and subsequent discussion cover topics such as the visual cognitive system's functioning, the eye-head motor control system, and potential research avenues. These findings deepen our understanding of human behavior and offer promising implications for behavior generation in human-robot interaction and human-centered artificial intelligence.

We perceive the colors of moving objects. The color and motion signals are initially processed separately in different parts of the brain and later combined to yield a unified percept, but its details are not fully understood. To elucidate the underlying mechanisms, aftereffects of direction-selective adaptation (DSA) were measured with functional MRI (fMRI) technique using isoluminant color-defined motion (CM) and luminance-defined motion (LM) stimuli. In contrast to psychophysical studies, prolonged adaptation (>9 s) to CM yielded a higher response to LM test (opposite from typical motion aftereffects), while LM test after adaptation to LM did not evoke a significant DSA aftereffect. Additional experiments by using low-contrast or slow speed LM adapting stimulus suggested that residual luminance in CM could cause the DSA, but they did not explain its polarity or differences among visual areas. An experiment with a short adaptation (3 s) showed a typical DSA aftereffect in V3AB, a part of motion processing stream, when both adapting and test stimuli were LM. Overall, our results indicate that luminance channel mainly contributes to the DSAs, but the results of prolonged (>9 s) fMRI adaptation suggest interactions between color and luminance motion mechanisms that were not identified in the previous studies, suggesting the need for further investigation.

Individuals have less desire for foods they eat repeatedly than for foods they have not eaten. This is called sensory-specific satiety (SSS), and it motivates people to eat a variety of foods. This psychological study examined the influence of a variety of food shapes on SSS using a four-shaped food product known as Chicken McNuggets^®. Twenty participants completed three phases: first rating, preload and second rating. During the first rating, participants ate one nugget and rated their feelings, such as pleasantness or boredom. During the preload phase, half of the participants consumed six nuggets of the same shape as that of the first rating. The other half ate six nuggets comprised of four different shapes. During the second rating, all participants ate a nugget of the same shape as that of their first rating and rated their feelings. The results showed that participants who had eaten only one shape had a greater decrease in pleasantness and an increase in boredom than those who had eaten four shapes. These findings provide evidence that SSS decreases with varied food shapes and support the view that food-shape variety acts as a cue for estimating food variety overall.

A fundamental role of the visual system is to transform pixel-based retinal images into the representation of objects. A key to understand this transformation is in intermediate-level cortical areas where the features extracted from an image are selectively pooled for the construction of "proto-objects." This short review introduces recent findings on intermediate-level cortical representation and discusses their essence towards understanding the abstraction of retinal images into objects. Recent physiological studies have reported that a population of neurons in intermediate-level visual cortex, V4, are capable of predicting figure and ground (FG) regions that provide the basis in the construction of a proto-object by defining its extent. The agreement in the characteristics of FG determination between the neural responses and perception strongly supports the crucial role of V4 neurons in FG perception. An important factor for the construction of a proto-object is its contour shape. Specifically, how the neurons in intermediate-level cortex code complex contours in natural scenes provides important clues for understanding the construction of proto-objects. A recent study reported that V4 neurons simultaneously code multiple contour features such as closure, curvature, orientation, and symmetry, which appears to be effective for the representation of complex contours. The result also raises a fundamental question on the representation of shape; whether they are coded by a combination of the geometric features such as curvature and orientation or by some other nonintuitive coding. These findings indicate a crucial role of a population of V4 neurons in the construction of proto-objects wherein FG regions are estimated and contour components are integrated.

There are two binocular cues for motion-in-depth, interocular velocity difference (IOVD) and changing disparity over time (CDOT). To understand how the visual system deals with information obtained from the world, investigation of available cues for certain functions is indispensable, particularly when there are more than one. We review studies to investigate how the two cues contribute to the perception of motion-in-depth, focusing on the method to isolate these cues. The summary suggests that it is likely that both of IOVD and CDOT cues contribute to motion-in-depth nontrivial way while IOVD might be more important.

The visual system has the ability to distinguish depth differences between stimuli with high precision on the basis on binocular disparities. Psychophysical studies have suggested that binocular depth perception depends not only on the given disparity but also on other factors, such as surrounding stimuli, the spatiotemporal conditions, and the disparity gradient. Here, we report that the similarity between two surfaces enhances the sensitivity to the relative depth between the surfaces. Experiment 1 investigated the effect of orientation on the sensitivity to detect the relative disparity between patches filled with gratings and Experiment 2 investigated the effect of color. The results showed that the sensitivity to disparity differences was higher when the two surfaces had the same orientation (Experiment 1) or the same color (Experiment 2) than when either orientation or color was different. Using random-dot stereograms, Experiments 3 and 4 investigated the influence of luminance and color borders on the perception of relative depth. The results showed that the sensitivity to the relative disparity was higher when the disparity discontinuity borders were at different locations from the location of luminance or color borders than when they were at the same locations. These results suggest that the visual system is sensitive to relative depth within the same surface more than to the relative depth between different surfaces.