Harvey is a historian of art, visual culture, and sound art, and also a sound- and visual-art practitioner. His research field is the visual and sonic culture of religion, principally. In his historical studies, he engages the imagery and sonorities of popular piety, the Judaeo-Christian scriptures, supernaturalist traditions, and working-class culture. His books include The Bible as Visual Culture (2013), Photography & Spirit (2007/10), The Appearance of Evil: Apparitions of Spirits in Wales (2003), Image of the Invisible: The Visualization of Religion in The Welsh Nonconformist Tradition (1999), and The Art of Piety: The Visual Culture of Welsh Nonconformity (1995). Harvey has also contributed numerous chapters and articles to books and journals including 'The Ghost in the Machine' in The Ashgate Research Companion to Paranormal Culture (Ashgate, 2013), 'Framing the Word' in Bible, Art, Gallery (Sheffield Academic Press, 2012), 'Visual Culture' in The Handbook of Research Methods in Religious Studies (Routledge, 2011), and 'The Bible and Art in Wales' in Imaging the Bible in Wales (University of Wales Press, 2010). He has also convened conferences including, most recently, 'The Noises of Art: Audiovisual Practice in History, Theory and Culture' (Aberystwyth University/The Courtauld Institute of Art, London, 2013), and delivered keynote and other scholarly papers at conferences held in the UK, Europe, and USA.