Visual field inhomogeneous in brain-computer interfaces based on rapid serial visual presentation

Objective. Visual attention is not homogeneous across the visual field, while how to mine the effective EEG characteristics that are sensitive to the inhomogeneous of visual attention and further explore applications such as the performance of brain-computer interface (BCI) are still distressing explorative scientists. Approach. Images were encoded into a rapid serial visual presentation (RSVP) paradigm, and were presented in three visuospatial patterns (central, left/right, upper/lower) at the stimulation frequencies of 10Hz, 15Hz and 20Hz. The comparisons among different visual fields were conducted in the dimensions of subjective behavioral and EEG characteristics. Furthermore, the effective features (e.g. SSVEP, N2pc and P300) that sensitive to visual-field asymmetry were also explored. Results. The visual fields had significant influences on the performance of RSVP target detection, in which the performance of central was better than that of peripheral visual field, the performance of horizontal meridian was better than that of vertical meridian, the performance of left visual field was better than that of right visual field, and the performance of upper visual field was better than that of lower visual field. Furthermore, stimuli of different visual fields had significant effects on the spatial distributions of EEG, in which N2pc and P300 showed left-right asymmetry in occipital and frontal regions, respectively. In addition, the evidences of SSVEP characteristics indicated that there was obvious overlap of visual fields on the horizontal meridian, but not on the vertical meridian. Significance. The conclusions of this study provide insights into the relationship between visual field inhomogeneous and EEG characteristics. In addition, this study has the potential to achieve precise positioning of the target's spatial orientation in RSVP-BCIs.

Is there a lower visual field preference in object affordances? A registered report.

It’s been repeatedly shown that pictures of graspable objects can facilitate visual processing and motor responses, even in the absence of reach-to-grasp actions, an effect often attributed the concept of affordances, originally introduced by Gibson (1979). A classic demonstration of this is the handle compatibility effect, which is characterised by faster reaction times when the orientation of a graspable object’s handle is compatible with the hand used to respond, even when the handle orientation is task irrelevant. Nevertheless, whether faster RTs are due to affordances or spatial compatibility effects has been significantly debated. In the proposed studies, we will use a stimulus-response compatibility paradigm to investigate firstly, whether we can replicate the handle compatibility effect while controlling for spatial compatibility. Here, participants will respond with left- or right-handed keypresses to whether the object is upright or inverted and, in separate blocks, whether the object is red or green. RTs will be analysed using repeated-measures ANOVAs. In line with an affordance account, we hypothesise that there will be larger handle compatibility effects for upright/inverted compared to colour judgements, as colour judgements do not require object identification and are not thought to elicit affordances. Secondly, we will investigate whether the handle compatibility effect shows a lower visual field (VF) advantage in line with functional lower VF advantages observed for hand actions. We expect larger handle compatibility effects for objects viewed in the lower VF than upper VF, given that the lower VF is the space where actions most frequently occur.

Facemasks Block Lower Visual Field in Youth Ice Hockey

Wearing a facemask (FM) reduces the spread of COVID-19, but it also blocks a person's lower visual field. Many new public safety rules were created in response to COVID-19, including mandated FM wearing in some youth sports like youth ice hockey. We hypothesized that FM wearing in youth hockey players obstructs the lower field of view and may impact safety. Youth hockey players (n = 33) aged 12.03 (1.6) years button press when they saw an LED on the floor turn on in two conditions (wearing FM or no FM) in random order. An interleaved one-up/one-down two-alternative-forced-choice adaptive staircase design was used. Visual thresholds were calculated for each condition and participant. The visual angle threshold (VAT) was determined using standing eye height and the linear distance from the tip of the skates to the visual threshold. Paired t-tests determined whether mask wearing changed the VAT. We modeled the probability a player could see the puck on their stick in four distinct scenarios to estimate the potential impact of FM wearing during hockey play. The average unmasked VAT (11.4 degrees) was significantly closer to the skates than the masked VAT (20.3 degrees) (p < 0.001). Our model indicated a significant reduction in ability to visualize the puck using peripheral vision when more upright while wearing a FM. FM wearing compromised their lower visual field, suggesting a downward head tilt may be necessary to see the puck. Playing ice hockey while wearing a FM may lead to unsafe on-ice playing conditions due to downward head tilt to see the puck.

Design of Electrode Placement for Presenting Phosphenes in the Lower Visual Field Based on Electric Field Simulation

Presenting visual information, called phosphenes, is a critical method for providing information on the position of obstacles for users of walking support tools for the visually impaired. A previous study has established a method for presenting phosphenes to the right, center, and left of the visual field. However, a method for presenting information on the position of obstacles around the feet using phosphenes, which is essential for the visually impaired, has not been clarified. Therefore, in this study, a method for presenting phosphenes in the lower visual field is presented, towards the aim of realizing a safe walking support tool. Electrode placement is proposed in this paper for the presentation of phosphenes to the right, center, and left of the lower visual field based on the electrode placement method used in the previous study, which presents the phosphene in three locations of the visual field. In addition, electric field simulation is performed, focusing on the electric field value on the eyeball surface, in order to observe whether the proposed electrode placement is able to stimulate the intended region. As a result, it is shown that the intended region on the eyeball surface can be stimulated locally with each of the proposed electrode placements.

Attention: Here, There and Everywhere: The Relationship between Emotional Images and Attention Distribution

<p>Within the field of cognitive psychology there are two opposing theoretical frameworks, the conceptual metaphor theory and the broaden-and-build theory, which attempt to explain the influence of emotionally valenced stimuli on attention distribution. The conceptual metaphor theory (Lakoff & Johnson, 1999) asserts that concrete concepts (e.g. vertical distance or brightness) are used as metaphors to scaffold mental representations of abstract concepts (e.g. love and power). These metaphors rely on sensorimotor information in order to be understood, and therefore are said to be embodied. The focus of this thesis is the “Good is Up, Bad is Down” conceptual metaphor. A central prediction of this theory is that emotionally valenced stimuli should activate the “Good is Up, Bad is Down” metaphor, and automatically shift vertical attention congruently. In contrast, the broaden-and-build theory (Fredrickson, 2004) is based on evolutionary principles (Frijda, 1986), with negative emotions associated with specific-action tendencies and positive emotions associated with diffuse-action tendencies. The main prediction derived from this theory is that when individuals are induced into positive emotions their attention is broadened, whereas when induced into negative emotions their attention is narrowed. The central aim of this thesis was to gather experimental data in support for either the conceptual metaphor theory or the broaden-and-build theory when using emotionally laden images to induce affect, compared to prior research, which has utilised valenced words. This thesis also aimed to examine the influence, if any, of both valence and arousal of the emotional images. The literature provides conflicting views on whether these constructs are orthogonal or interconnected, and as such what effect they have on evaluative processing. To date, research examining the conceptual metaphor theory or the broaden-and-build theory has not controlled for both valence and arousal in their experimental design. Two experiments were designed to assess both aims. In Experiment 1, emotionally valenced images were presented in either the upper or lower visual field, and participants were asked to categorise the image as “positive” or “negative” by pressing a designated key on a keyboard. In Experiment 2, the emotional images were displayed in the centre of the visual field for a fixed period of time, followed by the presentation of a target letter in either the upper or lower visual field. Participants responded by pressing the corresponding key to the target letter on a keyboard. Across both experiments no shifts in attention were congruent with the “Good is Up, Bad is Down” conceptual metaphor theory, indicating that the conceptual metaphor theory is not supported when utilising images. In contrast, Experiment 2 provided experimental data in support of the broaden-and-build theory, with participants responding faster to all target letters following high valenced images regardless of their position. Finally, this thesis provides support to the notion that valence and arousal are orthogonal constructs, independently influencing higher order cognitive processes such as attention.</p>

Attention: Here, There and Everywhere: The Relationship between Emotional Images and Attention Distribution

<p>Within the field of cognitive psychology there are two opposing theoretical frameworks, the conceptual metaphor theory and the broaden-and-build theory, which attempt to explain the influence of emotionally valenced stimuli on attention distribution. The conceptual metaphor theory (Lakoff & Johnson, 1999) asserts that concrete concepts (e.g. vertical distance or brightness) are used as metaphors to scaffold mental representations of abstract concepts (e.g. love and power). These metaphors rely on sensorimotor information in order to be understood, and therefore are said to be embodied. The focus of this thesis is the “Good is Up, Bad is Down” conceptual metaphor. A central prediction of this theory is that emotionally valenced stimuli should activate the “Good is Up, Bad is Down” metaphor, and automatically shift vertical attention congruently. In contrast, the broaden-and-build theory (Fredrickson, 2004) is based on evolutionary principles (Frijda, 1986), with negative emotions associated with specific-action tendencies and positive emotions associated with diffuse-action tendencies. The main prediction derived from this theory is that when individuals are induced into positive emotions their attention is broadened, whereas when induced into negative emotions their attention is narrowed. The central aim of this thesis was to gather experimental data in support for either the conceptual metaphor theory or the broaden-and-build theory when using emotionally laden images to induce affect, compared to prior research, which has utilised valenced words. This thesis also aimed to examine the influence, if any, of both valence and arousal of the emotional images. The literature provides conflicting views on whether these constructs are orthogonal or interconnected, and as such what effect they have on evaluative processing. To date, research examining the conceptual metaphor theory or the broaden-and-build theory has not controlled for both valence and arousal in their experimental design. Two experiments were designed to assess both aims. In Experiment 1, emotionally valenced images were presented in either the upper or lower visual field, and participants were asked to categorise the image as “positive” or “negative” by pressing a designated key on a keyboard. In Experiment 2, the emotional images were displayed in the centre of the visual field for a fixed period of time, followed by the presentation of a target letter in either the upper or lower visual field. Participants responded by pressing the corresponding key to the target letter on a keyboard. Across both experiments no shifts in attention were congruent with the “Good is Up, Bad is Down” conceptual metaphor theory, indicating that the conceptual metaphor theory is not supported when utilising images. In contrast, Experiment 2 provided experimental data in support of the broaden-and-build theory, with participants responding faster to all target letters following high valenced images regardless of their position. Finally, this thesis provides support to the notion that valence and arousal are orthogonal constructs, independently influencing higher order cognitive processes such as attention.</p>

Incremental Visual Occlusion During Split-Belt Treadmill Walking Has No Gradient Effect on Adaptation or Retention

Split-belt treadmills have become an increasingly popular means of quantifying ambulation adaptability. Multiple sensory feedback mechanisms, including vision, contribute to task execution and adaptation success. No studies have yet explored visual feedback effects on locomotor adaptability across a spectrum of available visual information. In this study, we sought to better understand the effects of visual information on locomotor adaptation and retention by directly comparing incremental levels of visual occlusion. Sixty healthy young adults completed a split-belt adaptation protocol, including a baseline, asymmetric walking condition (adapt), a symmetric walking condition (de-adapt), and another asymmetric walking condition (re-adapt). We randomly assigned participants into conditions with varied visual occlusion (i.e., complete and lower visual field occlusion, or normal vision). We captured kinematic data, and outcome measures included magnitude of asymmetry, spatial and temporal contributions to step length asymmetry, variability of the final adapted pattern, and magnitude of adaptation. We used repeated measures and four-way MANOVAs to examine the influence of visual occlusion and walking condition. Participants with complete, compared to lower visual field visual occlusion displayed less consistency in their walking pattern, evident via increased step length standard deviation ( p = .007, d = 0.89), and compared to normal vision groups ( p = .003 d = 0.81). We found no other group differences, indicating that varying levels of visual occlusion did not significantly affect locomotor adaptation or retention. This study offers insight into the role vision plays in locomotor adaptation and retention with clinical utility for improving variability in step control.

Natural Image Statistics for Mouse Vision

The mouse has dichromatic colour vision based on two different types of opsins: short (S)-and middle (M)-wavelength-sensitive opsins with peak sensitivity to ultraviolet (UV; 360 nm) and green light (508 nm), respectively. In the mouse retina, the cone photoreceptors that predominantly express the S-opsin are more sensitive to contrasts, and denser towards the ventral retina, preferentially sampling the upper part of the visual field. In contrast, the expression of the M-opsin gradually increases towards the dorsal retina that encodes the lower visual field. Such distinct retinal organizations are assumed to arise from a selective pressure in evolution to efficiently encode the natural scenes. However, natural image statistics of UV light have never been examined beyond the spectral analysis. Here we developed a multi-spectral camera and examined the UV and green image statistics of the same natural scenes. We found that the local contrast and the spatial correlation were higher in UV than in green for images above the horizon, but lower in UV than in green for those below the horizon. This suggests that the mouse retina is not necessarily optimal for maximizing the bandwidth of information transmission. Factors besides the coding efficiency, such as visual behavioural requirements, will thus need to be considered to fully explain the characteristic organization of the mouse retina.