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Temporary suppression of visual processing in an RSVP task: an attention blink?

Temporary suppression of visual processing in an RSVP task: an attention blink?. By Raymond, Shapiro, & Arnell JEP:HPP. Attention blink phenomenon. What is it? Why does it occur? What can we say about the mechanism of human attention from this?

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Temporary suppression of visual processing in an RSVP task: an attention blink?

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  1. Temporary suppression of visual processing in an RSVP task: an attention blink? By Raymond, Shapiro, & Arnell JEP:HPP

  2. Attention blink phenomenon • What is it? • Why does it occur? • What can we say about the mechanism of human attention from this? • How does this cognitive phenomenon help understand our everyday activities?

  3. Attention blink experiment • Coglab CD • You see a stream of 19 letters (110ms for each letter). • After seeing the stream , • Press J if J is present • Press K if K is present • Press J&K if both J and K are present. • Press nothing if you see neither J nor K.

  4. Manipulations • Presence / absence • In some trials, J and K are present • In some trials, only J is present • In some trials, only K is present • J-K separation • In some trials, 0, 2, 4, 6, and 8 letters separated J and K

  5. My results

  6. What do this result mean? • Why is it so difficult when J & K are separated only by a few letters? • What caused this “blink”?

  7. Raymond et al. • Exp. 1 • Stimuli • Randomly ordered streams of letters (11 letters in one sequence) • Task: • Identify the white target letter embedded in a stream of black letters, and identify the three letters presented immediately after the target letter. • Subjects: • 5 subjects

  8. Procedure: • 90 RSVP trials were given to each subject. • Each letter was presented for 15 ms with an inter-stimulius interval (ISI) of 75ms. • The target letter was randomly selected. • Ss were instructed to report the name of the white letter (the first target) and the names of the next three letters.

  9. Results • Results: • Those letters that followed immediately after the target were rarely reported. • The letters that came +5 or more after the target were often reported.

  10. What are possible explanations? • The task was too difficult • you had to report actual letters • Is this due to memory defect? (you forget the letters) • Is this due to a sensory factor (e.g., masking effect)?

  11. Exp. 2 • Task: • The target and probe letters were specified before the experiment. • Each letter was presented for 15 ms with an inter-stimulius interval (ISI) of 75ms. = Exp. 1

  12. Manipulations • Experimental condition: • Ss were asked to identify a white letter (target) embedded in a letter stream of black letters, and subsequently to respond if a X (probe letter) had been presented or not. • Control condition: • Ss did not need to report the white target letter, but just indicated whether a probe X had been present or not some time after the target white letter was shown.

  13. Participants • 10 subjects, 180 trials/subject. • Design • 90 trials  a probe was present; • 90 trials  a probe was absent • the probe was presented at each of the 9 position 10 times.

  14. E.g., target X; Probe Y • 0 separation ( -- XY ---) • 1 separation ( -- X-Y---) • 2 separation (-- X- -Y--) • 3 separation (-- X- - - Y --) • ….

  15. Results the post target deficit effect was observed only in the experimental condition but not in the control condition. Not a sensory mechanism, but an attentional mechanism is responsible for the post target deficit effect. It is not a memory factor, because the target and probe letters were specified prior to the experiment.

  16. Exp. 3 • Goal and manipulations • The blank interval was inserted between the white target letter and the probe letter at varying time intervals (0, 90, 180, 270ms).

  17. Logic: Time-related or event-related? • If the posttarget deficit is time-related, attenuated (gradual decrements of the posttarget deficit) time-dependent deficit should occur. (as in Exp. 2). • If the posttarget deficit is event related (related to the presentation of letters), then the posttarget deficit (attention) blink should disappear in the blank condition.

  18. Subjects • 10; 440 RSVP trials/subject • Procedure & Design • 440 RSVP trials; • 4 blank intervals (0, 90, 180, 270ms), each had 100 trials; among them half of the trials had a probe, and the remaining half did not have a probe. • 5 posttarget events (+1, +2, +3, +4, +7) were intermixed in each of the four blank intervals (10 trials each)

  19. 40 additional trials • the blank was presented at 450ms or 540 ms (20 trials each; and the probe was presented only in half of the trials; 10 trials each) • The probe was presented either at +1 or +2 serial position (how many events/letters you see after the target)

  20. 400 + 40 trials • 400 trials • 200 trials (a probe was present) • 4 blank intervals: 0, 90, 180, 270ms (50 trials each) • 200 trials (a probe was absent) • 4 blank intervals: 0, 90, 180, 270ms (50 trials each)

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