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Saccades actively maintain perceptual continuity

This study delves into whether saccades hinder or aid in maintaining perceptual continuity. Experiment designs, methods, and results provide insights into how saccades affect visual analysis and memory associations. Critiques offer valuable perspectives for further exploration.

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Saccades actively maintain perceptual continuity

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  1. Saccades actively maintain perceptual continuity John Ross & Anna Ma-Wyatt

  2. Overview • Introduction • Methods • Results • Discussion • Critique • joeLAB Preliminary Findings

  3. Introduction • 2 (opposing) views on saccades and perceptual continuity: • Saccades hinder perceptual continuity • Suppression of magnocellular pathway • Compression of perceived object position • Saccades help perceptual continuity • Memory for scenes built up over time across saccades • Overlap between programming an eye movement and deployment of attention in LIP

  4. Introduction • Purpose: To examine the question of whether saccades help or hinder perceptual continuity • Experiment 1: Do saccades help or hinder perception of immediately past perceptual states? • Experiment 2: Do saccades help or hinder learned associations?

  5. Methods: Experiment 1 • 3 bistable ambiguous stimuli Necker Cube Binocular rivalry Glass Line

  6. Methods: Experiment 1 • 3 conditions 1. Continuous 2. Intermittent 3. Saccade Fixate on cube (5s)  Cube disappears  Fixate on same spot (5s) Fixate Fixate on cube (5s)  Saccade  Fixate on peripheral target (5s)

  7. Results: Experiment 1 • Saccade condition: shortest state duration (most rapid reversal rate) • Intermittent condition: longest state duration

  8. Methods: Experiment 2 • McCollough Effect • 50s adaptation period; 5s alternation • Presentation of the 3 conditions of Exp. 1 (continuous, intermittent, saccade) while viewing test stimulus

  9. Results: Experiment 2 • Saccade condition: longest after-image persistence

  10. Results Summary • Experiment 1 state duration for ambiguous stimuli: Intermittent > Continuous > Saccade • Experiment 2 after-image duration for McCollough effect: Saccade > Intermittent > Continuous

  11. Discussion • Experiment 1 results suggest that saccades erase immediately past perceptual states that could inhibit visual analysis • May be explained by parietal neurons that shift receptive fields before the eyes move for a saccade Duhamel et al., 1992

  12. Discussion • Experiment 2 results suggest that saccades strengthen learned associations (e.g. McCollough effect) • Re-establishing position in the world • Frontal eye field neurons may control influence of saccades on memory • maintain a memory of the visual world in the absence of visual stimulation (e.g. when making a saccade away from the test stimulus)

  13. Critique • “Eye movements were not monitored, as all subjects were experienced in making voluntary saccades…” • “…and maintaining fixation between saccades”

  14. Critique • 3 subjects; 3 trials per condition • Experiment 1: voluntary vs. involuntary changes of state?

  15. Saccades and McCollough Effect: Preliminary Findings

  16. Special thanks to: • Joint Oculomotor Experimentation Laboratory • NSERC • Centre for Vision Research • Celeste McCollough d

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