Jun Saiki

• PhD
• Professor (Full) at Kyoto University

Humans flexibly allocate attention depending on the given context. The dominant view posits that attention is guided by spatial and temporal sensory contextual cues that directly specify the target location. In real-world scenarios, however, such contextual cues are not always accessible, posing a problem for identifying the current context. Here,...

Humans flexibly allocate attention depending on the given context. The dominant view posits that attention is guided by spatial and temporal sensory contextual cues that directly specify the target location. In real-world scenarios, however, such contextual cues are not always accessible, posing a problem for identifying the current context. Here,...

Ensemble perception refers to the ability to accurately and rapidly perceive summary statistical representations of specific features from a group of similar objects. However, the specific type of representation involved in this perception within a three-dimensional (3-D) environment remains unclear. In the context of perspective viewing with stere...

It has been reported that visual statistical learning (VSL) is facilitated in skewed distributions. However, it remains unclear whether enhancement of VSL in Zipfian distributions is due to consciousness of the regularities presented at high frequency. This study addressed this issue. We measured participants’ subjective confidence in regularities...

During the observation of a single object, orientation and spatial frequency are jointly coded in an early stage of visual processing, as is evident from studies on the aftereffects of specific combinations of both these features. However, they become independent in the decision-making stage because observers can identify one feature while ignoring...

Recent cultural studies have discussed universality and diversity in human behavior using numerous samples investigated worldwide. We aimed to quantitatively extend this discussion to various research activities in psychology in terms of geographic regions and time trends. Most psychology departments have specialists in various fields of psychology...

Attention plays a crucial role in cognition and behavior. To explain the cultural variability of attention, we postulated a general hypothesis of cultural adaptation, which assumes that the attentional mechanism co-evolves with objects in our environment. We employed a three-level approach composed of hypothesis-driven experiments, a large-scale da...

Research has confirmed that the visual working memory representation of objects’ roughness is robust against illumination changes in the human ventral visual cortex and intraparietal sulcus, but not yet against visual distractors during memory maintenance. Thus, this study investigated the effects of visual distractors on roughness-related brain re...

Background The wisdom of crowds and collective decision-making are important tools for integrating information between individuals, which can exceed the capacity of individual judgments. They are based on different forms of information integration. The wisdom of crowds refers to the aggregation of many independent judgments without deliberation and...

A recent study showed that objects' roughness (smooth or rough) was held in visual working memory (VWM) in the ventral visual cortex and the intraparietal sulcus (IPS). Here, we investigated the functional differences between these areas in the context of VWM of material properties. We focused on the process in which participants accurately extract...

Are visual representations in the human early visual cortex necessary for visual working memory (VWM)? Previous studies suggest that VWM is underpinned by distributed representations across several brain regions, including the early visual cortex. Notably, in these studies, participants had to memorize images under consistent visual conditions. How...

A key challenge for the visual system entails the extraction of constant properties of objects from sensory information that varies moment by moment due to changes in viewing conditions. Although successful performance in constancy tasks requires cooperation between perception and working memory, the function of the memory system has been under-rep...

Prior research has reported that the medial temporal, parietal, and frontal brain regions are associated with visual statistical learning (VSL). However, the neural mechanisms involved in both memory enhancement and impairment induced by VSL remain unknown. In this study, we examined this issue using event-related fMRI. fMRI data from the familiari...

Are visual representations in the human early visual cortex necessary for visual working memory (VWM)? Previous studies have suggested that what underlies VWM is distributed representations across brain regions, including the early visual cortex. Notably, in these studies, participants had to memorize a visual image as it is. However, in our daily...

Behavioral and neuroscience studies have shown that we can easily identify material categories, such as metal and fabric. Not only the early visual areas but also higher-order visual areas including the fusiform gyrus are known to be engaged in material perception. However, the brain mechanisms underlying visual short-term memory (VSTM) for materia...

We can incidentally learn regularities in a visual scene, and this kind of learning facilitates subsequent processing of similar scenes. One example of incidental learning is referred to as contextual cueing, a phenomenon in which repetitive exposure to a particular spatial configuration facilitates visual search performance in the configuration. P...

The nature of feature-bound object representations in visual working memory (VWM) remains unclear. Many studies claim that they are held by a resource-limited system and are fragile. Using a novel paradigm called the redundant feature reviewing task, the current study showed that color-shape binding representations for multiple objects are maintain...

Although it is well accepted that the formation of visual working memory (VWM) representations from simple static features is a rapid and effortless process that completes within several hundred milliseconds, the storage of motion information in VWM within that time scale can be challenging due to the limited processing capacity of the visual syste...

Glossiness is a surface property of material that is useful for recognizing objects and spaces. For glossiness to be effective across situations, our visual system must be unaffected by viewing contexts, such as lighting conditions. Although glossiness perception has constancy across changes in illumination, whether visual working memory also reali...

Mindfulness meditation consists of focused attention meditation (FAM) and open monitoring meditation (OMM), both of which reduce activation of the default mode network (DMN) and mind-wandering. Although it is known that FAM requires intentional focused attention, the mechanisms of OMM remain largely unknown. To investigate this, we examined striata...

This article reviews studies on feature integration in visual working memory, which is critical for various cognitive activities using visual information. Studies involving change detection and multiple object tracking tasks reported that feature-integrated object representations are successfully maintained, and that the parietal cortex plays a maj...

Feature–reward association elicits value-driven attentional capture (VDAC) regardless of the task relevance of associated features. What are the necessary conditions for feature–reward associations in VDAC? Recent studies claim that VDAC is based on Pavlovian conditioning. In this study, we manipulated the temporal relationships among feature, resp...

While some studies suggest cultural differences in visual processing, others do not, possibly because the complexity of their tasks draws upon high-level factors that could obscure such effects. To control for this, we examined cultural differences in visual search for geometric figures, a relatively simple task for which the underlying mechanisms...

In this study, we examined the neural correlates of implicit knowledge about statistical regularities of temporal order and item chunks using functional magnetic resonance imaging (fMRI). In a familiarization scan, participants viewed a stream of scenes consisting of structured (i.e., three scenes were always presented in the same order) and random...

This study was a case investigation of grapheme–texture synestheste TH, a female who subjectively reported experiencing a visual association between grapheme and colour/texture. First, we validated the existence of a synesthetic association in an objective manner. Involuntarily elicited experience is a major hallmark that is common to different typ...

Grapheme–color synesthesia is a neurological phenomenon where visual perception of letters and numbers stimulates perception of a specific color. Grapheme–color correspondences have been shown to be systematically associated with grapheme properties, including visual shape difference, ordinality, and frequency. However, the contributions of graphem...

The vanishing point seems to be a useful cue for understanding scenes at a glance. The closer the objects are, the smaller their sizes become. Because the resolution of central vision is higher than that of peripheral vision, seeing a vanishing point enables individuals to perceive the whole scene. Here, we examined whether vanishing points attract...

Studies have demonstrated that eye movements enhance visual memory. However, the role of eye movement in implicit learning is not clear. We investigated whether implicit learning of spatial configuration requires eye movement using the contextual cueing paradigm. Eye movements were restricted by instructing participants to maintain fixation on the...

Grapheme-color synesthesia is a condition in which visual perception of letters and numbers induces simultaneous perception of a given color. Previous studies have shown factors that affect synesthetic grapheme-color correspondence. Among them, some are systematically associated with grapheme properties: visual shape and ordinality (positions in a...

A saliency-based visual attention model can simulate human eye movement. The higher saliency of the visual location, the more it attracts visual attention. While saliency map is computed from local information, ensemble information reflects spatially distributed objects. In this study, we examined whether ensemble information, in addition to salien...

In visual memory, bindings of shape with its figure color (intrinsic binding) and with its background color (extrinsic biding) are qualitatively different. We investigated effects of intrinsic and extrinsic bindings in visual memory on perceptual identification of shape-color binding. Participants previewed a sample display composed of a nonsense f...

Many previous studies report that stimuli associated with reward capture attention (value-driven attentional capture; VDAC), regardless of task-relevant or task-irrelevant features. However, necessary conditions for the formation of the feature-reward association in VDAC remain unknown. Recent studies claim that VDAC is based on prediction-based as...

Implicit learning of visual contexts facilitates search performance—a phenomenon known as contextual cueing; however, little is known about contextual cueing under situations in which multidimensional regularities exist simultaneously. In everyday vision, different information, such as object identity and location, appears simultaneously and intera...

We examined whether visual statistical learning (VSL) produced implicit and/or explicit knowledge about temporal order information and scene chunks, using a rapid serial visual presentation target detection task and a two-alternative forced-choice (2AFC) familiarity test as indirect and direct measures of VSL, respectively. In the familiarization p...

Prior studies have shown that visual statistical learning (VSL) enhances familiarity (a type of memory) of sequences. How do statistical regularities influence the processing of each triplet element and inserted distractors that disrupt the regularity? Given that increased attention to triplets induced by VSL and inhibition of unattended triplets,...

Synesthesia is a neurological phenomenon in which certain types of stimuli elicit involuntary perceptions in an unrelated pathway. A common type of synesthesia is grapheme-color synesthesia, in which the visual perception of letters and numbers stimulates the perception of a specific color. Previous studies have often collected relatively small num...

The mechanism by which nonspatial features, such as color and shape, are bound in visual working memory, and the role of those features' location in their binding, remains unknown. In the current study, I modified a redundancy-gain paradigm to investigate these issues. A set of features was presented in a two-object memory display, followed by a si...

Recent studies have sought to determine which levels of categories are processed first in visual scene categorization and have shown that the natural and man-made superordinate-level categories are understood faster than are basic-level categories. The current study examined the robustness of the superordinate-level advantage in a visual scene cate...

Visual search asymmetry is a phenomenon in which search efficiency changes in accordance with a swapping target and distractor, and which has been observed with a variety of target types. Previous studies assume that search asymmetry is achieved due to the difference of activation, which is calculated by considering each feature separately (e.g., c...

Rewards shape the deployment of visual attention to particular objects. Growing evidence indicates that the stimulus previously associated with reward involuntary captures attention (value-driven attentional capture; VDAC, e.g., Anderson, 2013). However, little is known about what properties of the reward-associated feature elicit VDAC, even if thi...

Visual search performance is facilitated when fixed spatial configurations are presented repeatedly, an effect known as contextual cueing (Chun & Jiang, 1998). Although a previous study showed that contextual cueing occurred even when objects were jittered (Chun & Jiang, 1998, Experiment 6), it is not clear how variability influences contextual cue...

Binding of non-spatial features in visual working memory (VWM), and the role of location in binding, remain unknown. Empirical evidence for and against feature binding in VWM has been based on null results. Object file theory postulates that spatiotemporal location is critical in maintenance of feature binding in VWM, but no evidence has been provi...

Rewards affect the deployment of visual attention in various situations. Evidence suggests that the stimulus associated with reward involuntary captures attention (value-driven attentional capture; VDAC). Recent studies report VDAC even when the reward-associated feature does not define the target (i.e., task-irrelevant). However, these studies did...

We can rapidly and efficiently recognize many types of objects embedded in complex scenes. What information supports this object recognition is a fundamental question for understanding our visual processing. We investigated the eccentricity-dependent role of shape and statistical information for ultrarapid object categorization, using the higher-or...

In the present study, we investigated how feature- and location-based selection influences visual working memory (VWM) encoding and maintenance. In Experiment 1, cue type (color, location) and cue timing (precue, retro-cue) were manipulated in a change detection task. The stimuli were color-location conjunction objects, and binding memory was teste...

Previous studies have shown conflicting data as to whether it is possible to sequentially shift spatial attention among visual working memory (VWM) representations. The present study investigated this issue by asynchronously presenting attentional cues during the retention interval of a change detection task. In particular, we focused on two types...