Title: Multisensory Influences on Visual Attention
Author: Marcia Grabowecky
Affiliation: Department of Psychology, Northwestern University, USA.
Perceptual research has matured, and a great deal is now known about individual perceptual modalities, and about how attention functions within them. However, we experience the world as multisensory and integrated, and attention is most often directed to multisensory events. I will discuss some of our work over the last decade using visual search, attentional cuing, and binocular rivalry paradigms. Data from these paradigms suggests pervasive influences from auditory and haptic processing on visual perception and attention. Whereas some of these interactions depend on well-learned correspondences, such as the visual appearance of a cat and its accompanying “meow” vocalization, many of these multisensory interactions occur without our explicit knowledge of any reliable underlying relationship between visual and auditory or haptic information. Recently, intriguing evidence is accumulating to suggest that at least some of these multisensory interactions may depend on direct connections between early sensory cortical areas. I will present some evidence using electrocorticography data from patients with epilepsy to shed light on this speculation.
Title: Concealed by the Most Salient Structure in Visual Search
Author: Jing-Ling Li
Affiliation: Graduate Institute of Biomedical Sciences, China Medical University, Taiwan.
Visual search is usually more efficient if the searched target was salient or on a salient location. However, we found a counterintuitive phenomenon that a target is actually more difficult to find if it was placed on a salient collinear structure, which is called the collinear masking effect. We found that this collinear masking effect restricts specifically to perceptual law of good continuity, other salient structure created by feature contrast on orientation, color, or luminance dimensions induced facilitation rather than masking. Also, task requirements, predictability, and practice did not eliminate this collinear masking effect. The collinear masking effect can be observed within 40 ms presentation duration of the search display, suggesting that this effect is majorly based on stimulus-driven computation. Dichoptic presentation showed that the collinear masking effect requests of information from single eye, which implies critical involvement of the primary visual cortex. The data cumulated till now suggest that this collinear masking effect may relate to boundary formation. Our work reveals how object perception links to attentional capture, and in which conditions perceptual grouping can facilitate or impair attention selection.
Title: Attention at Locations Unattended
Author: Satoshi Shioiri
Affiliation: Research Institute of Electrical Communication, Tohoku University, Japan.
Attending on a spatial location in the visual field facilitates visual processing at the location, which is important feature for efficient visual processing. While a variety of attentional effects have been studied, basic features such as spatial modulation of attentional effect are still unclear. Particular interest is facilitation and inhibition around focus of attention. Some studies reported facilitation of area adjacent to attention focus while others reported lateral inhibition of attention effect. We investigated spatial spreads of attentional effect using electroencephalography (EEG), analyzing steady state visual evoked potential (SSVEP) and event related potential (ERP). SSVEP is a technique to realize measurements of attentional effect at unattended locations with stimuli tagged by temporal frequency and suitable for estimating attentional spreads around focus of attention. We succeeded to measure spatial characteristics of visual attention using SSVEP and compared with event related potential (ERP) measurements. We found that SSVEP showed facilitation around the attention focus while ERP showed lateral inhibition. We discuss the results in terms of difference in spatial spread of attention at different stages of visual processing.
Title: Consciousness Without Attention and Large Capacity Conscious Memory, Investigated with Metacognition
Author: Naotsugu Tsuchiya
Affiliation: School of Psychological Sciences, Monash University, Australia.
Do we consciously experience only those sensory inputs that we attend to? Or, do we enjoy substantial amount of unattended information in conscious experience? The necessity of top-down attention for conscious perception has been hotly debated in consciousness research. In this talk, we present two studies in which we incorporated trial-by-trial confidence rating to assess "metacognitive accuracy" as a proxy for the degree of conscious access to sensory information. In the first study, we examined how much we remember about the non-target distractor faces in a natural-scene face-search task (Kaunitz, Rowe and Tsuchiya 2016 PsychSci). In the second study, we examined whether face genders or color orientation of patches in the periphery can be consciously discriminated when they simultaneously perform a highly demanding task at the fixation. In both cases, we found that our memory and perception of faces under inattention is much better than what would be expected if attention is necessary for them and that subjects can access to these information consciously, proven by above chance metacognitive accuracy, consistent with a claim that consciousness without attention is possible and robust for a certain class of stimuli (Koch & Tsuchiya 2007 Tics).
Title: Consciousness at a Price: The Attentional Blink is a Cost of Awareness
Authors: Dominique Lamy, Eyal Ophir and Eyal Sherman
Affiliation: Department of Psychology, Tel Aviv University, France.
Our ability to process successive events occurring in close temporal proximity is limited. In particular, selecting a first event incurs a cost in perceptual processing of a second event. Here, we disentangle the roles of conscious perception of and spatial attention to the first event in eliciting this perceptual cost. We establish the existence of a "cost of awareness" (CoA) and demonstrate that this cost exhibits the core characteristics of the attentional blink (AB), including location specific-lag-1 sparing and performance recovery at long lags. Furthermore, we show that conscious perception of the first event is both necessary and sufficient for the perceptual deficit underlying the CoA and the AB to occur, whereas spatial attention to the first event is neither necessary nor sufficient. We thus conclude that the attentional blink is a cost of awareness. The reformulation of the AB as a cost of awareness constrains current models of the attentional blink and highlights the potential role of factors influencing subjective conscious experience in shaping our performance and alleviating limitations of our perceptual system when we interact with successive events.
Title: Behavioral Influences and Temporal Dynamics of Unconscious Salience Processing
Author: Po-Jang (Brown) Hsieh
Affiliation: Duke-NUS Medical School, Brain & Consciousness Lab.
Visual popout occurs when a unique visual target (e.g., a feature singleton) is present in a set of homogeneous distractors. However, the role of visual awareness in this process remains unclear. In a series of experiments, we showed that even though subjects were not aware of a suppressed feature singleton, it still can (1) attract subjects’ attention to enhance subsequent performance on an orientation-discrimination task; (2) enables a display to reach awareness faster, and particularly increase a location’s probability of gaining awareness first; (3) influences the direction and latency of saccades. We further demonstrated in an electroencephalography (EEG) experiment that the presence of a salient feature singleton elicited early ERP differences during unconscious perceptual processing. Temporally, ERP differences in the frontal electrodes were evident earlier than the occipital electrodes. In addition, alpha oscillatory power was lower when a feature singleton was present. Finally, we demonstrate that the P2 component amplitude in the frontal electrode is associated with both unconscious salience processing and stimulus awareness.