Dr Lisa Evans
My research interests are in the area of human episodic memory, which is memory for our personal past. One strand of research in this area aims to refine psychological models of memory to gain a better understanding of the processes that contribute to recognition memory judgments and how they relate to each other. Another question that I am investigating is how healthy individuals are able to selectively retrieve relevant information without retrieving a flood of irrelevant memories. All this research takes a multi-modal approach (behavioural, EEG, MEG and fMRI) which permits an integrated analysis of the processes, time course and brain regions implicated in episodic memory.
My second area of interest is in examining the cognitive deficits present in individuals within the schizophrenia spectrum and elucidating the potential link with clinical symptoms. In particular I am interested in deficits in the inhibition of responses to sensory stimuli, learning paradigms and episodic memory. This research has used a range of techniques (e.g. behavioural, pharmacological, EMG and EEG).
I supervise final year project students. Students have completed projects on various aspects of memory (e.g. false memory, reality monitoring, prospective), learning paradigms (e.g. Kamin blocking, latent inhibition), psychophysiological techniques (e.g. prepulse inhibition of the startle response); some of these projects have been in conjunction with schizotypy. I also supervise UROP students and visiting students and interns from other departments.
I also organise all the teaching that postgraduates give to undergraduates.
Selected publications (2014 onwards)
Full list of publications
Research topics and related papers
Currently the focus of my work is on human episodic memory, particularly memory retrieval. One strand of research is to refine psychological models of memory to gain a better understanding of the processes that contribute to recognition memory judgments and how they relate to each other. Electrophysiological research has been influential in suggesting that there are two distinct processes: recollection and familiarity, but it is controversial how these processes are related to each other. Using magnetoencephalography (MEG) indices of memory retrieval processes we have been able to adjudicate between different accounts and find strong support that recollection and familiarity make independent contributions to memory judgments. This was achieved by averaging measures of neural activity and contrasting across different conditions of interest.
Figure 1 – Event-Related Field (ERF) data taken from a recent MEG study examining the relationship between episodic memory processes (taken from Evans & Wilding, , Journal of Neuroscience, 2012).
In other work we are investigating memory control processes. Over time, a huge amount of episodic information is stored in memory, and different situations require the selective and strategic retrieval of specific elements of contextual information that are relevant to the task at hand. Healthy individuals have the ability to selectively retrieve relevant information without retrieving a flood of irrelevant episodic memories, indicating that episodic retrieval is effectively guided and constrained by control processes. Our work using EEG aims to identify and determine the functional significance of these control processes and the different stages of retrieval at which they operate.
Figure 2 – Event-Related Potential (ERP) data taken from Evans et al. (2010) where a putative index of recollection was examined to assess the degree to which participants could exert strategic control over retrieval when the degree of similarity of encoding operations was manipulated.
The other area of research that I am interested in is a) elucidating the cognitive deficits present in individuals within the schizophrenia spectrum, and b) how these might be associated with certain clinical symptoms. Most of this work has taken a dimensional approach to schizophrenia and measured schizotypy in healthy volunteers. In particular, I am interested in deficits in the inhibition of neural and muscular responses to sensory stimuli. Paradigms that I have used include prepulse inhibition of startle (PPI) and P50 event-related potential suppression (see Figure 3 for an example of this response). Using these paradigms I have demonstrated that individuals who score highly on certain dimensions of schizotypy exhibit parallel deficits to individuals with schizophrenia.
Figure 3 – The P50 response can be seen as a positive deflection maximal at 59 ms which is considerably smaller in amplitude after the test than conditioning stimulus, taken from Evans et al. (2007).
I am also interested in prediction error, which is the discrepancy between expectation and experience. By minimising this error an individual is able to improve their ability to predict events in their environment. It has been proposed that individuals with schizophrenia may demonstrate an abnormal use of this error signal which results in the formation of inappropriate associations which in turn gives rise to some of the psychotic symptoms. We have conducted research using paradigms such as latent inhibition and Kamin blocking to understand the relationship between deficits in these abilities and the dimensions of schizotypy.
More recently I have become interested in episodic memory in individuals in the schizophrenia spectrum. We have conducted behavioural and electrophysiological studies to examine reality monitoring, which is the ability to discriminate internally generated from external information, to determine if a problem in this aspect of memory is associated with a predisposition to certain symptoms such as hallucinations and delusions.
Wilding, E.L. & Evans, L.H. (2011-2013). Refining models of memory retrieval via real-time measures of neural activity. Funded by a BBSRC research grant (£210K).
Herron, J.E. & Evans, L.H. (2007-2008). Psychophysiological studies of memory for imagined and perceived events: The effects of schizotypy. Funded by the Bial Foundation (€50K).
Evans, L.H. (2005-2006). A multi-component analysis of personality correlates of sensory gating. Funded by an ESRC post-doctoral fellowship (£30K).
Marks, D., Snowden, R.J., Gray, N.S. & Evans, L.H. (2003-2004). Assessing the relationship between subjective validation, personality characteristics and beliefs in the paranormal. Funded by the Bial Foundation (€30K).
Mark Haselgrove (University of Nottingham)
Education & Employment
I studied Psychology at Cardiff University (1997-2000: BSc First Class Honours). I also completed a PhD at Cardiff University in Experimental Clinical Psychology under the supervision of Prof Bob Snowden and Prof Nicola Gray. Since completion of my PhD I have worked in the department as a Research Fellow on grants in the areas of Forensic Psychology, Cognitive Neuroscience of Attention and Memory and Clinical Psychology.
Manuscript Reviewing Activities
International Journal of Psychophysiology
Journal of Abnormal Psychology
Journal of Forensic Psychiatry and Psychology
Neuroscience and Biobehavioural Reviews
Personality and Individual Differences
Selected Conference Presentations
Evans, L.H. & Wilding, E.L. (2012). Neural evidence that recollection and familiarity are independent processes. SHARE: Learning and Memory in the Limbic System Conference, Cardiff.
Evans, L.H. & Wilding, E.L. (2012). Neural evidence that recollection and familiarity make independent contributions to recognition memory judgments. Cognitive Neuroscience Society Conference, Chicago, USA.
Evans, L.H. & Wilding, E.L. (2011). Recollection and familiarity: A magnetic declaration of independence. Memory workshop, Saarbrucken, Germany.
Evans, L.H. & Wilding, E.L. (2011). Dual-process theories of recognition memory: a magnetic declaration of independence. WICN conference, Deganwy.
Evans, L.H. & Wilding, E.L. (2010). Recollection and familiarity: A magnetic declaration of independence. MEGUK, Cardiff.
Evans L.H., Wilding E.L. & Herron, J.E. (2009). Shared and task-specific neural activation supporting episodic retrieval. Society for Neuroscience Conference, Chicago, USA.
Evans, L.H. & Herron, J.E. (2008). The influence of task instructions on electrophysiological correlates of memory retrieval. Cognitive Neuroscience Society Conference, San Francisco, USA.
Evans, L.H., Gray, N.S. & Snowden, R.J. (2006). Cognitive disorganisation is associated with a deficit in P50 suppression. Cognitive Neuroscience Society Conference, San Francisco, USA.
Evans, L.H., Gray, N.S. & Snowden, R.J. (2006). There are no robust associations between prepulse inhibition, P50 suppression and latent inhibition. British Association of Cognitive Neuroscience Conference, Coventry, UK.