5.2: Introduction

Psychedelic substances are serotonergic hallucinogens (e.g. psilocybin, i.e. ‘magic mushrooms’ and LSD, i.e. lysergic acid diethylamide) that exert widespread effects in the brain through activation of the serotonin 5-HT2A receptor found primarily on the fifth layer of the cortex, (Carhart-Harris et al., 2015) but also found within the limbic system and brain-stem (Kent, 2012; Carter et al., 2005). The excitation of these neurons results in the recruitment of different cell-types, (Martin & Nichols, 2016) and greatly alters the nature of communication between brain regions. Together, these dose-dependent effects make psychedelic substances primary candidates for manipulating cognitive mechanisms. For the purpose of this paper, the research methods proposed here are for investigating the low-dose effects of psilocybin, as opposed to including all serotonergic hallucinogens.

The psychedelic state is characterized by altered cognition, sensory perception, and emotionality, resulting in changes in one’s sense of self and perceptions of reality, (Nour, Evans, & Carhart-Harris, 2016; Letheby & Gerrans, 2017; Wittman, et al., 2007) as well as personality characteristics, beliefs, and social attitudes (Carhart-Harris, Erritzoe, Kaelen, & Watts, 2018; Bouso et al., 2015; Lerner & Lyvers, 2006). While clinical and neuroscience research has tracked dose-dependent changes in subjective-reports (Griffiths et al., 2011) and neurophysiology (Nichols et al., 2003), there is far less work looking at dose-dependent changes in cognitive processes. The field of psychedelic research will require a multitude of various methodologies to fully capture the diverse effects of psilocybin. While the efforts of this paper are focused on employing these methods for low-dose research, cognitive psychologists who are interested in psychedelic research should also consider using these methods for higher-dose effects as well.

Cognitive behavioral tasks may be especially fitting for microdosing research in their ability to track the onset and nature of changes in specific cognitive processes. The objective of this paper is to pair specific psychedelic drug effects with cognitive-behavioral tasks to elucidate the effects of microdosing. Cognitive data for microdosing research may be able to track changes that cannot be measured by subjective-report or neuroimaging alone. These methods are also important for answering practical questions about the effects of microdosing psilocybin or LSD on everyday functioning to help guide judgment on when and how to use them.

Leading research on the effects of these substances from neuroscience and clinical fields are presented and briefly summarized, followed by an introduction and explication of microdosing. Psychedelic drug effects are then further explicated and appropriately paired with cognitive behavioral tasks. Lastly, comments for employing these methods in future research and concluding remarks are presented.