Interhemispheric ERP asymmetries over inferior parietal cortex reveal differential visual working memory maintenance for fearful versus neutral facial identities

Abstract

The goal of the present investigation was to discover whether visual working memory maintenance for faces is modulated by facial expression using event-related potentials (ERPs). Each trial consisted of two sequential arrays, a memory array and a test array, each including either two or four faces with neutral or fearful expressions. The faces were displayed to the left and to the right of a central fixation cross. Two central arrows cued participants to encode one face or two faces displayed on one side of the memory array. The sustained posterior contralateral negativity (SPCN) component of the ERP time-locked to the onset of the memory array was used as an index of visual working memory maintenance. Visual working memory performance was quantified using indexes of memory capacity (Cowan's K and K-iterative), a standard index of sensitivity (d'), and reaction times (RTs). Relative to neutral faces, superior memory and longer change-detection RTs to fearful face identities were observed when two faces were displayed on the cued side of the memory array. Fearful faces elicited an enhanced SPCN relative to neutral faces, especially when only one face was displayed on the cued side of the memory array. These findings suggest increased maintenance in visual working memory of faces with a fearful expression relative to faces with a neutral expression and that the representational format in which fearful faces are stored in memory may be characterized by enhanced resolution relative to that subtended in the maintenance of neutral faces.

Interactions of emotion and anxiety on visual working memory performance

“…Indeed, even if external threat cues predominantly impaired visual memory performance (in the case of low anxious individuals), this also discords from evidence that threat signals generally should improve early information processing and sensory acquisition (Phelps et al, 2006), which we hypothesised might translate to greater visual memory performance as when emotional information itself is maintained (Sessa et al, 2011). This can be reconciled within the present study, if one assumes that the influence of external threat on sensory processing does not extend beyond initial perception to the level of visual memory performance.…”

“…This can be reconciled within the present study, if one assumes that the influence of external threat on sensory processing does not extend beyond initial perception to the level of visual memory performance. Indeed, whereas Sessa et al (2011) found strong evidence of improved maintenance, this may be due to the emotional information itself being memorised. In our study, emotion was incidental to the task, and so external threat exposure may only beneficially impact visual working memory when emotional material itself is maintained.…”

“…Typically, this is assessed in change detection paradigms where participants are shown items to be remembered and, after a short delay period, see a new set of items and respond whether any items have changed. Rather than threat and anxiety impairing visual memory ability, there is evidence that encoding and maintaining threatening faces actually improves memory performance compared with neutral faces (Sessa, Luria, Gotler, Jolicoeur, & Dell'Acqua, 2011). In addition, self-reported anxiety also appears to correlate positively with memory performance for nonaffective items (e.g., bar orientations; Moriya & Sugiura, 2012), although task-induced worry and state anxiety appear to have a contrary effect with reduced performance (Sari, Koster, & Derakshan, in press).…”

“…Following a delay period, participants were shown a test array where items either matched memory displays or differed, testing memory ability. We hypothesised that exposure to threat primes prior to memory arrays may transiently augment sensory information processing, resulting in improved perceptual encoding and subsequent visual memory performance compared with neutral primes (Sessa et al, 2011). In addition, we predicted that threat would impair performance in the additional irrelevant item condition where distracting items must be filtered out.…”

Worry is associated with impaired gating of threat from working memory.

“…A lateralized change detection working memory task, adapted from prior event-related potential (ERP) research by our group (Stout et al, 2013) and others (Sessa, Luria, Gotler, Jolicœur, & Dell'Acqua, 2011), enabled us to estimate the number of threat-related and emotionally-neutral faces stored in working memory (See Figure 1). This design enabled direct comparison with prior ERP research (e.g., Stout et al, 2013).…”