眼電図はビデオ式眼球運動測定装置と比較して小型化，軽量化，省電力化といった面で有利であり，バッテリー駆動で長時間計測が可能である。しかし，アンプの直流成分のゲインが小さい場合，サッカードと瞬目の波形の判別が難しいという問題がある。応用を考慮するとこれらの運動と固視の判別も重要であるため，本研究ではサッカード，瞬目，固視の眼電図波形の判別を試みた。眼電図とビデオ式眼球運動測定装置での同時計測を行い，ビデオ式眼球運動測定装置の測定結果に基づいて瞬目，固視の開始から 500 ms間の波形と，500 ms以上持続した固視の波形から無作為な開始時刻で 500 ms間の波形を抽出した。これらの波形をサンプルとして独立成分分析を用いて特徴ベクトルを計算し，特徴ベクトルを用いてサッカード，瞬目，固視を判別する決定木を学習させた。交差検証の結果，独立成分の次元は2次元から8次元の範囲で判別成績に大きな影響を与えない事，決定木を深くすると成績は向上するが9付近を超えて深くすると成績が低下する事，高周波ノイズが判別成績を低下させる事が示された。

Objective Assessing daily motor fluctuations is an important part of the disease management for patients with Parkinson's disease (PD). However, the frequent recording of subjective and/or objective assessments is not always feasible, and easier monitoring methods have been sought. Previous studies have reported that the spontaneous eye-blink rate (EBR) is correlated with the dopamine levels in the brain. Thus, the continuous monitoring of the EBR may be useful for predicting the motor status in patients with PD. Methods Electrooculograms (EOGs) were recorded for up to 7.5 hours from three PD patients using a wearable device that resembled ordinary glasses. An receiver operating characteristic (ROC) analysis was performed to compare the ability of the EBR estimates at each time-point (Blink Index) and the plasma levodopa levels to predict the motor status. Results The Blink Index was correlated with the plasma levodopa levels. When an indicator for the first hour of the observation period was included in the model, the Blink Index discerned wearing-off and dyskinesia as accurately as the plasma levodopa level. Conclusion Our study provides preliminary evidence regarding the utility of continuous EBR monitoring for the non-invasive evaluation of the motor status in patients with PD.

PsychoPy is an application for the creation of experiments in behavioral science (psychology, neuroscience, linguistics, etc.) with precise spatial control and timing of stimuli. It now provides a choice of interface; users can write scripts in Python if they choose, while those who prefer to construct experiments graphically can use the new Builder interface. Here we describe the features that have been added over the last 10 years of its development. The most notable addition has been that Builder interface, allowing users to create studies with minimal or no programming, while also allowing the insertion of Python code for maximal flexibility. We also present some of the other new features, including further stimulus options, asynchronous time-stamped hardware polling, and better support for open science and reproducibility. Tens of thousands of users now launch PsychoPy every month, and more than 90 people have contributed to the code. We discuss the current state of the project, as well as plans for the future.

Eye movement analysis is effective for investigating visual perception and cognition. The cost of conducting eye movement studies has decreased as a result of the recent release of low-cost commercial and open-source eye trackers. However, synchronizing visual stimulus presentation with eye movement recording is still difficult, particularly if the eye tracker does not come with a practical application programming interface. This paper introduces a Matlab/Octave toolbox named Sgttoolbox, which works in conjunction with the widely used experiment control library Psychtoolbox to control a cross-platform open-source eye tracker named SimpleGazeTracker, which is an eye-tracking application of GazeParser software. Hardware and software requirements for Sgttoolbox and its main functions are described. A test of temporal accuracy showed that eye movement sampling frequency was stable when stimulus presentation and recording were performed on a single PC, although better performance was obtained when presentation and recording were performed on separate PCs. Transferring the latest eye position from SimpleGazeTracker to Psychtoolbox script takes 2 to 4 ms on average, which causes a delay in drawing multiple visual stimuli when recording and stimulus presentation were performed on a single PC. When such a transfer delay is not importnat, Sgttoolbox would be a good choice for Psychtoolbox users who wish to conduct eye-tracking studies.

Eye movement analysis is an effective method for research on visual perception and cognition. However, recordings of eye movements present practical difficulties related to the cost of the recording devices and the programming of device controls for use in experiments. GazeParser is an open-source library for low-cost eye tracking and data analysis; it consists of a video-based eyetracker and libraries for data recording and analysis. The libraries are written in Python and can be used in conjunction with PsychoPy and VisionEgg experimental control libraries. Three eye movement experiments are reported on performance tests of GazeParser. These showed that the means and standard deviations for errors in sampling intervals were less than 1 ms. Spatial accuracy ranged from 0.7° to 1.2°, depending on participant. In gap/overlap tasks and antisaccade tasks, the latency and amplitude of the saccades detected by GazeParser agreed with those detected by a commercial eyetracker. These results showed that the GazeParser demonstrates adequate performance for use in psychological experiments.

Saccade trajectory often curves away from a previously attended, inhibited location. A recent study of curved saccades showed that an inhibitory effect prevents ineffective reexamination during serial visual search. The time course of this effect differs from that of a similar inhibitory effect, known as inhibition of return (IOR). In the present study, we examined whether this saccade-related inhibitory effect can operate in an object-based manner (similar to IOR). Using a spatial cueing paradigm, we demonstrated that if a cue is presented on a placeholder that is then shifted from its original location, the saccade trajectory curves away from the original (cued) location (Experiment 1), yet the IOR effect is observed on the cued placeholder (Experiment 2). The inhibitory mechanism that causes curved saccades appears to operate in a location-based manner, whereas the mechanism underlying IOR appears to operate in an object-based manner. We propose that these inhibitory mechanisms work in a complementary fashion to guide eye movements efficiently under conditions of a dynamic visual environment.

'Perisaccadic mislocalization' is an illusion in which a stimulus presented briefly near the time of saccade onset is mislocalized. The amount of mislocalization depends on the stimulus location and the stimulus onset time relative to saccade onset. It is unclear whether perisaccadic mislocalization distorts the shape perception of a single object. To investigate this problem, we asked participants to report whether the apparent shape of a triangle presented for 10 ms before saccade was slanted in the same direction or the opposite direction as the saccade. The results showed that the apparent shape of the triangle was distorted in the direction opposite to the saccade. We compared this apparent distortion with the mislocalization of a perisaccadic vertical bar, and found that the time-course and direction of the distortion were similar, although the amount of distortion was smaller for the triangle. A hypothetical explanation for these results based on the forward/inverse optics model was discussed.

A recent study proposed that saccade trajectories often curve away from previously fixated locations during visual search because of the inhibitory mechanism which prevents inefficient reexamination of rejected distractors. In the present study, we examined whether visual contexts influence saccade trajectories as is the case with other inhibitory effects in visual search (e.g., inhibition of return). Computer-generated natural scenes were used as search stimuli and participants were required to look for a toy car in the scene. The results showed that the saccade trajectories were affected by at least three previous fixations and the effect decreased exponentially with the number of intervening fixations. These results are consistent with the findings in the previous study using abstract stimuli (the O among Cs search task). The relationships between saccade curvature and other inhibitory effects in visual search are discussed.

A saccade trajectory often curves away from the location of a non-target stimulus that appears before saccade execution. Spatial inhibition may prevent the saccade from moving toward the non-target stimulus. However, little is known about how simultaneous inhibition for multiple locations affects saccade trajectories. In this study, we examined the effects from two inhibited locations on saccade trajectories. The results show that the saccade trajectories depend on the inhibited locations, and the effect of inhibiting two locations on the trajectory was a summation of the effect of inhibiting each location. A simulation study using the initial interference model also suggests that the effect of each inhibition was summed up to modulate the initial saccade direction.

Recent studies have suggested that the apparent shape of a perceptually organized object flashed immediately before saccade is not distorted although a perisaccadic flash is mislocalized as if the visual space is compressed toward the goal of the saccade. We report that the apparent width of a Kanizsa illusory rectangle flashed in the perisaccadic period was compressed as much as that of a control stimulus that did not induce illusory rectangle, while that of a rectangle with real contour was less compressed. Our results imply that the process of saccadic compression of visual space completes faster than the interpolation process of illusory contours.