Mechanisms of working memory and their modulation by emotion

The aim of this thesis was to examine the possibility that sub-mechanisms of Short-Term or Working Memory (WM) can be selectively affected by task variables such as processing requirements, or situational variables such as positive or negative mood. The model of WM, developed by Baddeley and colleagues (Baddeley and Hitch, 1974; Baddeley, 2000) was taken as the basis for conceptualising the componential architecture of WM. It is proposed that individual WM components, i.e. the executive attention component, the verbal and the spatial storage components, could be systematically modulated by emotions. The first 2 studies investigate the differential involvement of the Central Executive component in tasks that have been reported to be differentially affected by mood. It has been argued that analytical tasks make greater demands on the Central Executive (CE) and therefore alternative demands on the CE will disrupt such tasks. The detrimental effect of positive mood on analytical tasks is due to the disruptive effect of this type of mood on CE function. Using a dual-task paradigm, it was demonstrated that an analytical reasoning task was more disrupted by a concurrent WM task than was a creative task, i.e. a demonstration that the CE is more involved in analytical tasks. Measures of brain electrical potentials demonstrated a parallel effect at the cortical level. The following studies examined other WM components, the verbal and spatial "slave" mechanisms and the possibility that they may be differentially modulated by emotion. Recent behavioural, psychophysiological and neuroimaging evidence suggests that spatial but not verbal, WM system is largely reliant on visual attention. It has also been shown that certain emotions, i.e. anxiety or fear, may be intrinsically associated with visual attention. On the basis of this overlap, it was predicted that induced anxiety/ fear would selectively modulate spatial WM, with little effect on verbal WM performance. An n-back task allowing of fine-grained dissociation of verbal and spatial WM was developed and three studies examined the effects of threat of shock on verbal and spatial n-back WM performance. The studies confirmed the prediction, showing that spatial WM performance was impaired in conditions of threat, while verbal WM performance remained unchanged. A number of analyses emphasised the relationship between anxiety and the decrement in spatial n-back performance. The presence of anxiety was objectively validated via physiological recordings. The literature contains suggestions that, in contrast to the selective disruption of spatial WM in threat-anxiety observed in our studies, trait and test anxiety tend to affect verbal WM more than spatial WM. Therefore, in a subsequent study verbal and spatial n-back WM performance was contrasted in high vs. low trait anxiety individuals. It was found that verbal and spatial WM were not differentially disrupted in individuals high with trait anxiety. The final study aimed to determine whether interhemispheric asymmetry models in emotion and WM could serve as a neuroanatomical explanation of the selective effect of anxiety on spatial WM. The study employed neuroimaging technology to compare the activation of regions of the frontal cortex in the two hemispheres in the verbal and spatial n-back tasks employed earlier. The anatomical regions of interest were chosen on the basis of neuroanatomical models of brain laterality in emotion. The results do not contain reliable patterns of frontallateralization. Hence, they provide little support to laterality-based accounts of the interaction between spatial WM and anxiety. These findings support the hypothesis that WM components can be selectively modulated by factors such as affective state. They also suggest that attentional-executive mechanisms may not be fully distinct from the storage systems, as claimed in the original characterisation of WM

The coupling between spatial attention and other components of task-set: a task switching investigation

Is spatial attention reconfigured independently of, or in tandem with, other task-set components when the task changes? We tracked the eyes of participants cued to perform one of three digit-classification tasks, each consistently associated with a distinct location. Previously we observed, on task switch trials, a substantial delay in orientation to the task-relevant location and tendency to fixate the location of the previously relevant task – “attentional inertia”. In the present experiments the cues specified (and instructions emphasised) the relevant location rather than the current task. In Experiment 1, with explicit spatial cues (arrows or spatial adverbs), the previously documented attentional handicaps all but disappeared, whilst the performance “switch cost” increased. Hence, attention can become decoupled from other aspects of task-set, but at a cost to the efficacy of task-set preparation. Experiment 2 used arbitrary single-letter cues with instructions and a training regime that encouraged participants to interpret the cue as indicating the relevant location rather than task. As in our previous experiments, and unlike in Experiment 1, we now observed clear switch-induced attentional delay and inertia, suggesting that the natural tendency is for spatial attention and task-set to be coupled and that only quasi-exogenous location cues decouple their reconfiguration

More attention to attention? An eye-tracking investigation of selection of perceptual attributes during a task switch

This article may not exactly replicate the final version published in the APA journal. It is not the copy of record.Switching tasks prolongs response times, an effect reduced but not eliminated by active preparation. To explore the role of attentional selection of the relevant stimulus attribute in these task-switch costs, we measured eye fixations in participants cued to identify either a face or a letter displayed on its forehead. With only 200 ms between cue and stimulus onsets, the eyes fixated the currently relevant region of the stimulus less and the irrelevant region more on switch than on repeat trials, at stimulus onset and for 500 ms thereafter, in a pattern suggestive of delayed orientation of attention to the relevant region on switch trials. With 800 ms to prepare, both switch costs and inappropriate fixations were reduced, but on switch trials participants still tended (relative to repeat trials) to fixate the now-irrelevant region more at stimulus onset and to maintain fixation on, or refixate, the irrelevant region more during the next 500 ms. The size of this attentional persistence was associated with differences in performance costs between and within participants. We suggest that reorientation of attention is an important, albeit somewhat neglected and controversial, component of advance task-set reconfiguration and that the task-set inertia (or reactivation) to which many attribute the residual task-switch cost seen after preparation includes inertia in (or reactivation of) attentional parameters

Proactive inhibitory control: a general biasing account

Flexible behavior requires a control system that can inhibit actions in response to changes in the environment. Recent studies suggest that people proactively adjust response parameters in anticipation of a stop signal. In three experiments, we tested the hypothesis that proactive inhibitory control involves adjusting both attentional and response settings, and we explored the relationship with other forms of proactive and anticipatory control. Subjects responded to the color of a stimulus. On some trials, an extra signal occurred. The response to this signal depended on the task context subjects were in: in the ‘ignore’ context, they ignored it; in the ‘stop’ context, they had to withhold their response; and in the ‘double-response’ context, they had to execute a secondary response. An analysis of event-related brain potentials for no-signal trials in the stop context revealed that proactive inhibitory control works by biasing the settings of lower-level systems that are involved in stimulus detection, action selection, and action execution. Furthermore, subjects made similar adjustments in the double-response and stop-signal contexts, indicating an overlap between various forms of proactive action control. The results of Experiment 1 also suggest an overlap between proactive inhibitory control and preparatory control in task-switching studies: both require reconfiguration of task-set parameters to bias or alter subordinate processes. We conclude that much of the top-down control in response inhibition tasks takes place before the inhibition signal is presente

Face recognition and brain potentials: Disruption of configural information reduces the face inversion effect

Copyright © 2012 Cognitive Science Society.The face inversion effect (FIE) refers to the decline in performance in recognizing faces that are inverted compared to the recognition of faces in their normal upright orientation (Yin, 1969). Event-related potentials (ERPs) were recorded while subjects performed an Old/New recognition study on normal and Thatcherised faces presented in upright and inverted orientation. A large difference in processing between normal upright faces and normal inverted faces was observed at occipital-temporal sites about 165 ms following stimulus onset, mainly in the right hemisphere. Thus electrophysiological activity, which corresponds to the previously described N170, had larger amplitude and was delayed for normal inverted faces as compared to normal upright ones. By contrast, the activity for Thatcherised inverted faces was not significantly changed or delayed as compared to Thatcherised upright stimuli. These results combine to show how the effect of face inversion on the N170 is reliably greater when the faces are normal rather than Thatcherised. Finally, these finding complement, at a neural level, our behavioral studies which suggest that the loss of some configural information affects the FIE

The face inversion effect and evoked brain potentials: Complete loss of configural information affects the N170

Copyright © 2012 Cognitive Science Society.The face inversion effect (FIE) is a reduction in recognition performance for inverted faces compared to upright faces that is greater than that typically observed with other stimulus types (e.g. houses; Yin, 1969). Nevertheless, the demonstration that the inversion effect in recognition memory can be as strong with images of dogs as with faces when the subjects are experts in specific dog breeds (Diamond & Carey, 1986), suggests that there may be other factors, such as expertise, which give rise to the FIE. Event-related potentials (ERPs) were recorded while subjects performed an Old/New recognition study on normal and scrambled faces presented in upright and inverted orientations. We obtained the standard result for normal faces: The electrophysiological activity corresponding to the N170 was larger and delayed for normal inverted faces as compared to normal upright ones. On the other hand, the ERPs for scrambled inverted faces were not significantly larger or delayed as compared to scrambled upright stimuli. These results, in combination, show how the effect of inversion on the N170 is reliably greater when the faces are normal compared to scrambled, which suggests the disruption of configural information affects the FIE.University of Exete

Perceptual learning and inversion effects: Recognition of prototype-defined familiar checkerboards.

PublishedJournal ArticleResearch Support, Non-U.S. Gov'tThe face inversion effect is a defection in performance in recognizing inverted faces compared with faces presented in their usual upright orientation typically believed to be specific for facial stimuli. McLaren (1997) was able to demonstrate that (a) an inversion effect could be obtained with exemplars drawn from a familiar category, such that upright exemplars were better discriminated than inverted exemplars; and (b) that the inversion effect required that the familiar category be prototype-defined. In this article, we replicate and extend these findings. We show that the inversion effect can be obtained in a standard old/new recognition memory paradigm, demonstrate that it is contingent on familiarization with a prototype-defined category, and establish that the effect is made up of two components. We confirm the advantage for upright exemplars drawn from a familiar, prototype-defined category, and show that there is a disadvantage for inverted exemplars drawn from this category relative to suitable controls. We also provide evidence that there is an N170 event-related potential signature for this effect. These results allow us to integrate a theory of perceptual learning originally proposed by McLaren, Kaye, and Mackintosh (1989) with explanations of the face inversion effect, first reported by Yin.University of ExeterNational Key Fundamental Research (973) Progra

Detection of experimental ERP effects in combined EEG-fMRI: evaluating the benefits of interleaved acquisition and Independent Component Analysis

Copyright © 2011 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Clinical Neurophysiology . Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Clinical Neurophysiology, 2011 Vol. 122 Issue 2, pp. 267-77 DOI: http://dx.doi.org/10.1016/j.clinph.2010.06.033Objective The present study examined the benefit of rapid alternation of EEG and fMRI (a common strategy for avoiding artifact caused by rapid switching of MRI gradients) for detecting experimental modulations of ERPs in combined EEG–fMRI. The study also assessed the advantages of aiding the extraction of specific ERP components by means of signal decomposition using Independent Component Analysis (ICA). Methods ‘Go–nogo’ task stimuli were presented either during fMRI scanning or in the gaps between fMRI scans, resulting in ‘gradient’ and ‘no-gradient’ ERPs. ‘Go–nogo’ differences in the N2 and P3 components were subjected to conventional ERP analysis, as well as single-trial and reliability analyses. Results Comparable N2 and P3 enhancement on ‘nogo’ trials was found in the ‘gradient’ and ‘no-gradient’ ERPs. ICA-based signal decomposition resulted in better validity (as indicated by topography), greater stability and lower measurement error of the predicted ERP effects. Conclusions While there was little or no benefit of acquiring ERPs in the gaps between fMRI scans, ICA decomposition did improve the detection of experimental ERP modulations. Significance Simultaneous and continuous EEG–fMRI acquisition is preferable to interleaved protocols. ICA-based decomposition is useful not only for artifact cancellation, but also for the extraction of specific ERP components

How does response inhibition influence decision-making when gambling? (dataset)

Behavioural data, skin-conductance data, eye movement data, and R scripts (analyses) for eight behavioural experiments.Dataset relating to 'How does response inhibition influence decision-making when gambling?’research paper published in the Journal of Experimental Psychology: Applied. The paper is available in ORE: http://hdl.handle.net/10871/15841Behavioural data, skin-conductance data, eye movement data, and R scripts (analyses) for eight behavioural experiments. Experiment documentation is included as well.​ This data is related to the article 'How does response inhibition influence decision-making when gambling?' published in Journal of Experimental Psychology: Applied.Economic and Social Research Council (ESRC)European Research Council (ERC)Biotechnology and Biological Sciences Research Council (BBSRC)British Academy/Leverhulme Gran