How we change what others think, feel, believe and do
The Comma Effect
When writing a large number, commas are often used to make the price easier to read. However, it can also make the price seem more than if no comma is used.
A car salesperson omits commas on the car price stickers, for example showing $3245 rather than Â£3,245.
A real estate agent omits commas, for example showing $1230000, rather than $1,230,000.
A high-end manufacturer of personal clothing deliberately includes commas to accentuate how 'reassuringly expensive' their clothes are.
Commas create breaks in reading, making the price seem to be made of multiple parts. Removing the commas makes the number a single unit.
Commas also make the price a little longer and so make it seem 'bigger'. Removing the comma makes the number physically smaller and so can seem less.
A further effect is that a long number can be confusing and so lead the reader to pay less attention to it (rather than admit they are unsure of the price).
A similar effect happens with decimal points. For example $123 seems less than $123.00, mostly because it is shorter
Coulter, K.S., Choi, P. and Monroe, K.B. (2012). Comma N' cents in pricing: The effects of auditory representation encoding on price magnitude perceptions, Journal of Consumer Psychology, 22, 3, 395-407