Mental Shopping Calculations: A Transcranial Magnetic Stimulation Study

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neuroeconomics

Background:

• Assessing discount prices is crucial for consumer behavior but its neural basis is unclear.
• The posterior parietal cortex (PPC), particularly the supramarginal gyrus (SMG), is implicated in mental arithmetic.
• Previous research suggests the right SMG is vital for multi-digit calculations, but its role in discount arithmetic remains unknown.

Purpose of the Study:

• To investigate the neural mechanisms underlying discount arithmetic in a shopping context.
• To determine if the supramarginal gyrus (SMG) is involved in calculating sale prices.
• To compare the neural processes of discount calculations with those of simple addition/subtraction.

Main Methods:

• Utilized repetitive transcranial magnetic stimulation (rTMS) to modulate activity in the left and right supramarginal gyrus (SMG).
• Participants performed discount calculations (e.g., price reductions) and simple arithmetic tasks in a simulated shop environment.
• Employed neuronavigated rTMS for precise stimulation of targeted brain regions within the PPC.

Main Results:

• Discount calculations preferentially engaged the left supramarginal gyrus (SMG).
• Asymmetric activation of the SMG was observed during complex discount arithmetic, unlike simpler calculations.
• Simple price addition tasks did not show the same asymmetric SMG involvement.

Conclusions:

• The neural mechanisms for discount arithmetic differ from those for standard addition or subtraction.
• The supramarginal gyrus (SMG) plays an asymmetric role in complex shopping-related calculations.
• Findings contribute to neural models of mathematical cognition and offer insights into consumer decision-making.