Dave M. Stampe

Visual Span in Expert Chess Players: Evidence From Eye Movements:

The reported research extends classic findings that after briefly viewing structured, but not random, chess positions, chess masters reproduce these positions much more accurately than less-skilled players. Using a combination of the gaze-contingent window paradigm and the change blindness flicker paradigm, we documented dramatically larger visual spans for experts while processing structured, but not random, chess positions. In addition, in a check-detection task, a minimized 3 × 3 chessboard containing a King and potentially checking pieces was displayed. In this task, experts made fewer fixations per trial than less-skilled players, and had a greater proportion of fixations between individual pieces, rather than on pieces. Our results provide strong evidence for a perceptual encoding advantage for experts attributable to chess experience, rather than to a general perceptual or memory superiority.

The perceptual aspect of skilled performance in chess: Evidence from eye movements

Expert and intermediate chess players attempted to choose the best move in five chess positions while their eye movements were monitored. Experts were faster and more accurate than intermediates in choosing the best move. Experts made fewer fixations per trial and greater amplitude saccades than did intermediates, but there was no difference in fixation duration across skill groups. Examining the spatial distribution of the first five fixations for each position by skill group revealed that experts produced more fixations on empty squares than did intermediates. When fixating pieces, experts produced a greater proportion of fixations on relevant pieces than did intermediates. It is argued that expert chess players perceptually encode chess configurations, rather than individual pieces, and, consequently, parafoveal or peripheral processing guides their eye movements, producing a pattern of saccadic selectivity by piece saliency.

Heuristic filtering and reliable calibration methods for video-based pupil-tracking systems

Methods for enhancing the accuracy of fixation and saccade detection and the reliability of calibration in video gaze-tracking systems are discussed. The unique aspects of the present approach include effective low-delay noise reduction prior to the detection of fixation changes, monitoring of gaze position in real time by the operator, identification of saccades as small as 0.5° while eliminating false fixations, and a quick, high-precision, semiautomated calibration procedure.

Saccadic Inhibition in Voluntary and Reflexive Saccades

The present study investigated saccadic inhibition in both voluntary and stimulus-elicited saccades. Two experiments examined saccadic inhibition caused by an irrelevant flash occurring subsequent to target onset. In each trial, participants were required to perform a single saccade following the presentation of a black target on a gray background, 4 to the left or to the right of screen center. In some trials (flash trials), after a variable delay, a 33-msec flash was displayed at the top and bottom third of the monitor (these regions turned white). In all experimental conditions, histograms of flash-to-saccade latencies documented a decrease in saccadic frequency, forming a dip, time-locked to the flash and occurring as early as 6070 msec following its onset. The fast latency of this effect strongly suggests a low-level, reflex-like, oculomotor effect, which was referred to as saccadic inhibition. A novel procedure was developed to allow comparisons of saccadic inhibition even across conditions, which in the absence of a flash (no-flash trials) produce dissimilar saccadic reaction times (SRTs) distributions. Experiment 1 examined the effects of the fixation stimulus on saccadic inhibition by contrasting three conditions: a gap condition (fixation stimulus disappeared 200 msec prior to target onset), a step condition (offset of the fixation stimulus was simultaneous with target onset), and an overlap condition (the fixation stimulus remained on for the duration of the trial). The overlap condition produced substantially stronger saccadic inhibition, relative to the gap and the step conditions. Experiment 2 contrasted the saccadic inhibition effect obtained for prosaccades (saccades aimed at the target) with the effect obtained for antisaccades (i.e., saccades aimed away from the same target). The onset of saccadic inhibition was earlier, and its magnitude was stronger, for antisaccades, relative to prosaccades. The plausibility that the superior colliculus is the neurophysiological locus of the saccadic inhibition effect was explored.

Saccadic inhibition in reading

In 5 experiments, participants read text that was briefly replaced by a transient image for 33 ms at random intervals. A decrease in saccadic frequency, referred to as saccadic inhibition, occurred as early as 60-70 ms following the onset of abrupt changes in visual input. It was demonstrated that the saccadic inhibition was influenced by the saliency of the visual event (Experiment 3) and was not produced in response to abrupt but irrelevant auditory stimuli (Experiment 1). Display changes restricted to an area either inside or outside the perceptual span required for normal reading produced strong saccadic inhibition (Experiment 2). Finally, Experiments 4 and 5 demonstrated higher level cognitive or attentional modulation of the saccadic inhibition effect.

Perceptual automaticity in expert chess players: Parallel encoding of chess relations

A check detection task in a 5 × 5 section of the chessboard, containing a King and one or two potential checking pieces was employed. The checking status (i.e., the presence or absence of a check) and the number of attackers (one or two) were manipulated. It was found that the reaction time cost for adding a distractor was differentially greater inno trials thanyes trials for novice, but not for expert, chess players. In addition, we contrasted standard check detection trials with trials in which one of two attackers was cued (colored red) and the task was to determine the checking status of the cued attacker while ignoring the other attacker. We documented a Stroop-like interference effect on trials in which a cued nonchecking attacker appeared together with an attacker that was checking (i.e., incongruent). These findings suggest automatic and parallel encoding procedures for chess relations in experts.

Selection By Looking: A Novel Computer Interface And Its Application To Psychological Research

Abstract Real time monitoring of a subject’s gaze position on a computer display of response options may form an important element of future computer interfaces. Response by gaze position can also be a useful tool in psychological research, for example in a visual search task. Experimental tasks reported include visual search, and typing from an alphabetic menu. A lexical decision study revealed gaze response RT to be much more powerful than button press RT and new phenomena including self-correction were observed. Methods of improving response reliability are introduced, including drift correction by dynamic recentering, gaze aggregation, and automated selection.

Saccadic Inhibition in Complex Visual Tasks

Several gaze contingent studies that used a fixed delay between physical eye movements and a display change documented a dip in the fixation duration distributions (e.g., Blanchard et al. 1984; McConkie et al. 1985; van Diepen et al. 1995). In a study by van Diepen et al. (1995), a moving mask paradigm was employed in which subjects searched line drawings of everyday scenes for non-objects. The appearance of the mask was delayed relative to the end of a saccade (beginning of fixation) by 17, 46, 76 or 121 msec. All fixation duration distributions in the masking conditions exhibited a dip with longer masking delays resulting in the dip occurring at longer fixation durations. In contrast, a no-mask condition did not produce a dip. Similar effects in reading were reported by Blanchard et al. (1984), and McConkie et al. (1985). In both these studies the text was masked at a fixed delay from the end of the saccade, and the fixation duration distributions exhibited dips. McConkie et al. (1992) interpreted these dips as reflecting a disruption to automatic, parallel encoding or registration processes that are time locked to the onset of the visual pattern on the retina. Processing disruption causes an eye movement disruption after a constant transmission delay in the neural system.

Chapter 17 – Using the Saccadic Inhibition Paradigm to Investigate Saccadic Control in Reading

Publisher Summary Models of saccadic control in reading differ dramatically with respect to the hypothesized role of visuo-spatial attention in the programming and execution of eye movements. The attentional guidance model postulates tight coupling between attention and saccadic control in reading. An early version of this model argued that an attention shift in the direction of the next saccade occurs prior to its execution. This model assumes that attention is initially centered on the foveated word during fixation. One clear prediction that can be derived from the attentional guidance model is the occurrence of perceptual enhancement in the direction of the next saccade because of the preallocation of attention to the target of the saccade. Based on the attentional guidance model, it is predicted that if the probe is presented late in the fixation following the preallocation of attention to the next saccadic target, faster probe detection reaction times should be obtained when the probe is displayed in a location congruent with the direction of reading than when it is presented in the opposite direction. If, however, the probe is presented early in the fixation, before attention is preallocated, no such difference should be seen.

Influence of stimulus characteristics on the latency of saccadic inhibition.

Participants read or performed visual search while the normal task display was replaced for 33 ms by a transient image at random intervals. This produced a sharp reduction in saccadic frequency (saccadic inhibition) beginning as early as 70 ms following the display change. It was found that the latency of inhibition onset was determined by the difference between the normal and transient images, with changes in high spatial frequency content of the display resulting in longer latencies than changes in low spatial frequencies. Luminance changes evoked the fastest inhibition onset regardless of the spatial frequency content of the display change.