Figure 1.

Schematic illustration of the experimental setup. The ∼1-mm-thick aluminum panels of the electrically-grounded Faraday shielding provides an electromagnetically “quiet” environment. Three orthogonal sets of square coils ∼2 m on edge, following the design of Merritt et al. (1983), allow the ambient geomagnetic field to be altered around the participant’s head with high spatial uniformity; double-wrapping provides an active-sham for blinding of experimental conditions (Kirschvink, 1992b). Acoustic panels on the wall help reduce external noise from the building air ventilation system as well as internal noise due to echoing. A non-magnetic chair is supported on an elevated wooden base isolated from direct contact with the magnetic coils. The battery-powered EEG is located on a stool behind the participant and communicates with the recording computer via an optical fiber cable to a control room ∼20 m away. Additional details are available in Figure 2. This diagram and the center figure for the visual abstract was modified from the figure “Center of attraction,” by C. Bickel (Hand, 2016), with permission.