Why Free Shipping is So Appealing: A Brain Activity Study

Researchers affiliated with South Korea's Korea Brain Research Institute (KBRI) and other institutions have published a study in PLOS One titled "Neural and behavioral evidence of free shipping on consumer decision making," which analyzes why people react strongly to free shipping from the perspectives of behavior and brain activity.

In online shopping, consumers react strongly not only to the product price but also to the presence or absence of shipping fees. Even if the total amount including shipping fees is exactly the same, people tend to prefer the option of free shipping, but the psychological mechanism behind this has not been fully elucidated until now.

The research team investigated how shipping fees affect consumer decision-making using fMRI (functional magnetic resonance imaging), which visualizes brain activity.

In the experiment, 38 participants were subjected to an fMRI scan while making purchasing decisions for shoes. With the total payment amount consistently fixed at 50,000 won, they were presented with combinations of shoe prices and five shipping fee patterns (free, 2,000 won, 4,000 won, 6,000 won, 8,000 won) and asked to evaluate their purchase intent for each.

Considering the price combinations in Japanese Yen, it would be as follows:

Base price 5,000 yen + Free shipping = Total 5,000 yen

Base price 4,800 yen + Shipping 200 yen = Total 5,000 yen

Base price 4,600 yen + Shipping 400 yen = Total 5,000 yen

Base price 4,400 yen + Shipping 600 yen = Total 5,000 yen

Base price 4,200 yen + Shipping 800 yen = Total 5,000 yen

As a result of the experiment, behavioral data confirmed that purchase intent scores significantly decreased as shipping fees increased. However, there was no statistically significant difference between free shipping (average 2.57) and the lowest shipping fee of 2,000 won (average 2.55), with the difference becoming prominent when compared to conditions with shipping fees of 4,000 won or more.

On the other hand, in the metric of purchase intent score divided by reaction time (RIS), free shipping surpassed all other conditions, supporting how consumers prefer free shipping quickly and with less hesitation.

Next, the analysis of brain activity revealed by fMRI showed that the neural mechanisms consumers use when choosing free shipping differed depending on the amount of the shipping fee being compared.

First, when comparing free shipping with the lowest shipping fee (2,000 won), positive responses were observed in the medial prefrontal cortex (mPFC), precuneus, and inferior parietal lobule in the brain for free shipping. This suggests that consumers find strong emotional appeal and reward value in the zero price of 'free'.

Conversely, when the comparative shipping fee was moderate (4,000 won), the dominance of emotion-related areas decreased, and instead, the ventrolateral prefrontal cortex (VLPFC), involved in cognitive control and information re-evaluation, was strongly activated. This indicates that as the proportion of shipping fees increased, the decision-making mechanism shifted from emotional judgment to a more cautious cognitive process of logically evaluating the overall price structure.

Furthermore, in comparisons with high shipping fee conditions such as 6,000 won and 8,000 won, areas related to the execution of decision-making, such as the precentral gyrus (motor cortex), were activated, showing a tendency to quickly proceed with a purchase for the free shipping option when faced with high shipping costs.