Document Type


Degree Name

Master of Science (MSc)



Program Name/Specialization

Cognitive Neuroscience


Faculty of Science

First Advisor

Philip Servos

Advisor Role

Philip Servos


Purpose: The time-course needed to elicit tactile inhibition of return (IOR) has not been well-defined due to the paucity of research in this area especially studies investigating spatial discrimination. Reportedly tactile IOR uses higher-order mental representations to orient attention spatially yet the properties of low-level dermatomal maps may better account for how IOR orients tactile attention in space although its contribution is unclear. The present study sought to establish a time-course that evokes IOR in a unimodal tactile spatial discrimination task and decouples the contribution of the dermatome from higher-order representations. Methods: Two conditions containing distinct tactile cue-target paradigms designed to tap into either the whole finger representation (Finger trial) and its response gradient or the dermatomal representation (Location trial) were applied to the index and middle finger-tips of both hands of 17 participants. Targets appeared at a cued or uncued finger following an inter-stimulus interval (ISI; 150, 600, or 1200 ms) for Finger trials and they appeared at cued or uncued locations after an ISI within a single finger-tip for Location trials. Results: At ISIs of 1200 ms IOR and facilitation of response times (RTs) were elicited for cued and uncued homologous Finger trials respectively. As ISIs increased, RTs for uncued homologous and adjacent Finger trials linearly decreased and increased respectively. Thus, Finger trial type trends exhibited a non-linear response gradient but they were not different from those of Location trials, specifically cued and uncued Location trials mirrored cued and uncued homologous Finger trials. While no facilitation and IOR occurred between Location trials, cued and uncued trials showed trends typical of IOR. Conclusion: We showed that tactile IOR can be elicited in a unimodal spatial discrimination task and that tactile spatial attention, oriented via IOR, is likely driven by low-level dermatomal maps.

Convocation Year


Convocation Season