Objective: The objective of this study was to investigate the relationship between the number of sites of spinal dysfunction and a range of measures of cognitive processing. Methods: This double-blind, randomized, observational pilot study was performed at a chiropractic college clinical training facility. Thirty volunteers with clinical evidence of cervical spinal joint dysfunction participated. Subjects were classified into 2 groups depending on whether they exhibited signs of cervical spinal joint dysfunction at one or more sites. A range of computer-based tasks was used to determine simple reaction time (RT), choice RT, probe RT, and inhibition of a preplanned response. Results: Multiple sites of cervical spinal joint dysfunction were related to impaired cortical processing as revealed by significantly higher loads on central capacity, significantly less accurate response selection, and a trend toward more variable performance of an anticipated response. Multiple sites of cervical spinal joint dysfunction do not appear to be related to the speed of response selection or the ability to inhibit a preplanned response. Conclusion: This pilot study provides a context for the improvements in cortical processing observed after cervical spine adjustment. It shows that probe RT may be a useful tool in further studies examining the effects of cervical spine manipulation of joint dysfunction and the associated effect on cognitive function.