How low can you go? Changing the resolution of novel complex objects in visual working memory according to task demands

Abstract

In three experiments we manipulated the resolution of novel complex objects in visual working memory (WM) by changing task demands. Previous studies that investigated the trade-off between quantity and resolution in visual WM yielded mixed results for simple familiar stimuli. We used the contralateral delay activity as an electrophysiological marker to directly track the deployment of visual WM resources while participants preformed a change-detection task. Across three experiments we presented the same novel complex items but changed the task demands. In Experiment 1 we induced a medium resolution task by using change trials in which a random polygon changed to a different type of polygon and replicated previous findings showing that novel complex objects are represented with higher resolution relative to simple familiar objects. In Experiment 2 we induced a low resolution task that required distinguishing between polygons and other types of stimulus categories, but we failed in finding a corresponding decrease in the resolution of the represented item. Finally, in Experiment 3 we induced a high resolution task that required discriminating between highly similar polygons with somewhat different contours. This time, we observed an increase in the item’s resolution. Our findings indicate that the resolution for novel complex objects can be increased but not decreased according to task demands, suggesting that minimal resolution is required in order to maintain these items in visual WM. These findings support studies claiming that capacity and resolution in visual WM reflect different mechanisms.

The interplay of language and visual perception in working memory

“…One possibility is that participants may be able to tradeoff between these two parameters. Some studies have shown that the quantity-quality tradeoff is under volitional control (Allon, Balaban, & Luria, 2014;Fougnie, Cormiea, Kanabar, & Alvarez, 2016;Machizawa, Goh, & Driver, 2012). However, there is controversy around this effect with another share of studies not finding it (He, Zhang, Li, & Guo, 2015;Murray, Nobre, Astle, & Stokes, 2012;Zhang & Luck, 2011).…”

Audiovisual sentence recognition not predicted by susceptibility to the McGurk effect

“…At least one recent neuroimaging study supports the hypothesis that different neural mechanisms may mediate the integration of congruent versus incongruent visual information with auditory signals. Using fMRI, Erickson et al (2014) showed that distinct posterior superior temporal regions are involved in processing congruent AV speech and incongruent AV speech when compared to unimodal speech (acoustic-only and visual-only). Left posterior superior temporal sulcus (pSTS) was recruited during congruent bimodal AV speech.…”

The contralateral delay activity as a neural measure of visual working memory

“…However, a recent study demonstrated that while the CDA amplitude for random polygons may increase following task related resolution demands, it could not be decreased to the level of simple items such as colors. In this study (Allon et al, 2014), lowering the resolution demands was manipulated by asking subjects to monitor for a category change (e.g., between a polygon and a color). Thus, there was no need for maintaining any fine detailed information.…”

“…This example (adapted from Allon et al, 2014) is a grand average of 20 participants, at the PO7/PO8 electrodes, where the CDA is usually most pronounced. Subjects were presented with 3 colors for 200 ms, and had to memorize them during the 900-ms retention interval.…”