Investigating Neural Responses Underlying Product Valuation in The
Real-World Using Wireless Electroencephalography and Eye-Tracking
Abstract
Research in freely moving participants demonstrated that eye-movement
related potentials (EMRPs) obtained during wireless EEG and eye-tracking
can resolve low versus higher subjective value (SV) of products within
200 ms of first viewing. It remains unknown whether neural components
underpinning SV are computed linearly or in distinct clusters. A limited
stimulus value range may have prevented detection of linear
discrimination of EMRP components by SV. The residual presence of
oculomotor artefacts could have contributed to the lack of
discrimination of EMRPs for individual SVs. The present study
investigated whether EMRPs during product viewing would encode SVs
linearly by expanding retail-value range and implementing guided-saccade
artefacts removal. Participants viewed 216 product images in a
mock-gallery. Continuous 64-channel wireless EEG and eye-tracking data
were recorded. Willingness-to-pay was evaluated in an auction,
categorising products by SV. Adaptive Spatial Filtering removed
oculomotor artefacts from guided-saccade recordings. EMRPs were analysed
using independent component (IC) and clustering analysis. Four ICs
between 50 ̵̵ 230 ms resolved product SVs. One IC showed linearly
decreasing activity paralleling increasing SV, with strongest activation
for low-value. Other ICs responded preferentially to medium-value. ICs
resolving early SVs (50 ̵̵ 60 ms) differentiated the low-value category
from other categories. Cortical components elicited during free-viewing
of products in quasi-naturalistic settings were mostly tuned to specific
bands of SV with only one IC representing SV linearly. SVs appear to be
formed automatically during initial product viewing and are represented
on a coarse value grid, with the lowest SV products being processed
earliest.