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Role of Attention in the Temporal Dynamics of Post-Iconic Visual Memory Stores

Authors:

Abstract

We compared scanning of working memory for simple geometric shapes in cued (location, neutral) and non-cued (control) conditions to investigate the role of attention in the time course of visual working memory. A memory array of 4 items preceded a probe item at varying inter-stimulus intervals (ISIs), ranging from 520 to 5000ms, in the control condition, and in the cued conditions the array preceded a cue at varying ISIs, followed by the probe after 300ms. The location cue pointed to one of the 4 array items, either matching or mismatching the probe. The neutral cue pointed toward all four locations of the memory array. Observers reported whether the probe matched or mismatched the memory array. Response reaction times were collected, and comparison effects (CE) were computed by subtracting average reactions times for matched from mismatched memory array-probe pairings. Similar to previous findings (Jacob, Breitmeyer & Treviño, 2013), CEs in the control condition varied systematically across ISIs, likely reflecting fluctuations in attention and working memory content. The CEs in the location-cued condition followed the same temporal pattern as the control condition, but with dampened fluctuations, terminated by 4000ms. As expected, the location cue utilizes spatial attention to compare the cued item and the probe, reducing memory load. This is likely to reflect spatial attention overriding the effects of attention to WM content. In contrast, the CEs in the neutral-cued condition showed CE fluctuations with higher amplitude for later ISIs. The neutral cue enhances processing of the content of working memory, amplifying CEs as ISIs increase. Our results suggest that attention plays a role in in determining stages of information processing in working memory.
Jane Jacob1, Christianne Jacobs1, Bruno G. Breitmeyer1, 2 & Juha Silvanto1
1. Visual Cognition Lab, Department of Psychology, University of Westminster, UK
2. Department of Psychology & Center for Neuro-Engineering and Cognitive Science, University of Houston, USA
Background
Procedure
A memory scanning experiment was conducted with three conditions:
control, neutral cue and location cue.
Results and Discussion
Traditionally visual short-term memories (VSTMs) are divided into:
Visual iconic memory - lasts about 500 ms (Averbach & Coriell, 1961; Becker, Pashler & Anstis,
2000; Di Lollo, 1977; Sperling, 1960)
Visual working memory - estimated to last from one to several seconds (O’Herron &
von der Heydt, 2009; Sligte, Scholte & Lamme, 2009; Zhang & Luck, 2009)
Comparison tasks show evidence of three (Jacob, Breitmeyer & Treviño, 2013) or four (Jacob,
Breitmeyer & Treviño, 2014) stages of visual memory.
References
Averbach, E., & Coriell, A.S. (1961). Short-term memory in vision. Bell System Technical Journal, 40, 309-328.
Becker, M.W., Pashier, H., & Anstis, S.M. (2000). The role of iconic memory in change-detection tasks. Perception, 29, 273-286.
Di Lollo, V. (1977). Temporal characteristics of iconic memory. Nature, 267, 241-243.
Jacob, J., Breitmeyer, B. G., & Treviño, M. (2013). Tracking the first two seconds: three stages of visual information processing?. Psychonomic bulletin & review, 20(6), 1114-1119.
Jacob, J. & Breitmeyer, B. G. (2014). The First Four Seconds: An Assessment of Post-Stimulus Processing in Visual Short-Term Memories. Poster presented at the annual Vision Sciences Society (VSS)
meeting. Naples, FL, May 10-15.
O’Herron, P., & von der Heydt, R. (2009). Short-term memory for figure-ground organization in the visual cortex. Neuron, 61, 801-809.
Sligte, I.G., Scholte, H.S., & Lamme, V.A.F. (2009).V4 activity predicts the strength of visual short-term memory representations. The Journal of Neuroscience, 29: 3, 7432-7438.
Sperling, G. (1960). The information available in brief visual presentations. Psychological Monographs, 74, 1–29.
Zhang, W., & Luck, S.J. (2009). Sudden death and gradual decay in visual working memory. Psychological Science, 20:4, 423-428.
300
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450
RT (ms)
ΔRT
Figure 4 Figure 3 Figure 5
Figure 2
Figure 1
Reaction times (RTs) to the probe were
measured in each task. Comparison effects
were computed as the difference between RTs
(ΔRTs ) to probe when it matched or did not
match one of the items in VWM or the display.
i.e. ΔRT = RTmismatch - RTmatch
Comparison Effects Results:
A 3 (Condition: control, neutral-cue, location-cue) x 10(ISI) repeated-measures ANOVA was performed on ΔRTs
(difference between RTs for congruent and incongruent memory display and probe pairing).
Main effects of condition [F(2,22)= 7.949, p=0.003]
Main effect of SOA [F(9,99)= 3.360, p=0.001]
Condition x SOA interaction, quadratic trend [F(1,11)= 9.011, p=0. 012] (see Figures 3, 4 and 5)
Similar to previous findings (Jacob, Breitmeyer & Treviño, 2013), comparison effects (CEs) in the control
condition fluctuated across ISIs.
Compared to CEs in the control condition, the CEs in the location-cued condition had lower amplitude in its
fluctuations, and the CEs diminished by 4000 ms. As expected, the location cue leads the observer to utilize
spatial attention to make a judgement between the cued item and the probe, reducing the amount of
information that needs to be maintained in memory.
In contrast, the CEs in the neutral-cued condition showed CE fluctuations with higher amplitude for later
SOAs. When the neutral cue appears, there is an amplification of CEs (see Figure 6), particularly as ISIs increase.
The neutral cue may result in enhanced processing of the content of working memory.
Taken together, our results suggest that fluctuations in cognitive processing is present as information is
processed and maintained over time, and attention plays a role in the amplitude of these fluctuations. Figure 6
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