Participants
A total of 30 right-handed individuals with no history of psychiatric or
neurological disorders and normal vision (or vision corrected to normal)
were recruited for the study. After providing written informed consent,
each participant was compensated with ¥75. Ultimately, 28 participants
(18 female, mean age = 21.6 years, SD = 1.5 years) were included
in the sample, as two participants were excluded due to excessive EEG
artifacts. This study was approved by the local Human Ethics Committee
for Human Research, and it was conducted in accordance with the
guidelines of the Declaration of Helsinki and its subsequent amendments.
Stimuli, apparatus, andprocedure
Participant completed the experiment in a quiet and soundproof
laboratory, individually. They were asked to select pictures in four
different choice set sizes, and then fill out a choice overload
questionnaire to evaluate their experience (Fig. 1A ). The
experiment was managed by E-Prime 2.0 (Psychology Software Tools, Inc.,
Pittsburgh, PA), which controlled the presentation and timing of the
stimuli.
In the choice task, each trial consisted of three main stages: fixation
(1s), image presentation stage (10s + 0.5s mask) and response (3s)
(Fig. 1B ). During the image presentation stage, participants
were shown sets of natural landscape images and were asked to select the
one they preferred. The sets size varied, containing 4, 8, 12, or 16
clear images, while non-target images were mosaicked (Fig. 1C
and D ). The 10-second duration of the image presentation period was
determined based on a pilot experiment, allowing participants enough
time to make decisions without feeling rushed, and to make use of the
period for information processing. The mask was used to reduce the after
effect of image presentation. All pictures were obtained from the free
image material website
(https://www.pexels.com/zh-cn/)
with a total of 800 pictures. These images were standardized to 236 ×
177 pixels. Each image was only presented once in the same condition.
During the response stage, participants used the mouse to select their
preferred image from the current selection set. Each condition contained
50 trials, resulting a total of 200 trials. The order of the four
conditions was counterbalanced across participants.
Upon the completion of each condition in the choice task, participants
were asked to rate the difficulty of selection on a 7-point scale,
together with their positive (including satisfaction with the final
choice, pleasure, and satisfaction with the selection process) and
negative emotions (including regret, hesitation, and frustration), as
well as their inclination to avoid making a choice (for example,
delaying or abandoning the choice). Additionally, they were prompted to
assess whether the choice sets contained the ”right amount of options”
on a 7-point scale.