Abstract
One way to explore how prior sensory and motor events impact eye movements is to ask someone to look to targets located about a central point, returning gaze to the central point after each eye movement. Concerned about the contribution of this return to center movement, Anderson et al. (2008) used a sequential saccade paradigm in which participants made a continuous series of saccades to peripheral targets that appeared to the left or right of the currently fixated location in a random sequence (the next eye movement began from the last target location). Examining the effects of previous saccades (n−x) on current saccade latency (n), they found that saccadic reaction times (RT) were reduced when the direction of the current saccade matched that of a preceding saccade (e.g., two left saccades), even when the two saccades in question were separated by multiple saccades in any direction. We examined if this pattern extends to conditions in which targets appear inside continuously marked locations that provide stable visual features (i.e., target “placeholders”) and when saccades are prompted by central arrows. Participants completed 3 conditions: peripheral targets (PT; continuous, sequential saccades to peripherally presented targets) without placeholders; PT with placeholders; and centrally presented arrows (CA; left or right pointing arrows at the currently fixated location instructing participants to saccade to the left or right). We found reduced saccadic RT when the immediately preceding saccade (n−1) was in the same (vs. opposite) direction in the PT without placeholders and CA conditions. This effect varied when considering the effect of the previous 2–5 (n−x) saccades on current saccade latency (n). The effects of previous eye movements on current saccade latency may be determined by multiple, time-varying mechanisms related to sensory (i.e., retinotopic location), motor (i.e., saccade direction), and environmental (i.e., persistent visual objects) factors.
Highlights
The ability to direct our gaze to relevant stimuli within the environment is an important part of the process through which we detect and perceive visual information and interact with the world around us
When examining the effect of the immediately preceding saccade on current saccade latency, we found that in both the peripheral targets (PT) without placeholders and central arrow conditions, saccadic reaction times were faster when the immediately preceding saccade was in the same direction as the current saccade
We found differences in the overall reaction times across the three conditions, with the shortest saccade latencies observed in the PT without placeholders condition and the longest latency observed in the central arrow condition
Summary
The ability to direct our gaze to relevant stimuli (e.g., locations, objects, events) within the environment is an important part of the process through which we detect and perceive visual information and interact with the world around us. As a way to circumvent the requirement for a return of gaze to a central position between saccade events, Anderson et al (2008) employed a random walk consecutive saccade paradigm in which three participants (two of which were authors) made a continuous series of saccades (200 per run; participants completed 60 or 120 runs for a total of 12,000 or 24,000 saccades) to targets that appeared to the left or right (1.4◦) of the currently fixated location in a random sequence. Each successive target appeared a constant distance to the left or right of the currently fixated location on a random basis, such that any saccade could well be followed by a saccade in the same or opposite direction. It is important to note that the random walk paradigm permits an analysis of the independent effect of any number of preceding saccades’ directions
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