Here are three behavioural biases that could be impacting your spending:

Batteries not included

All-in behaviour is when a purchase involves costs that seem unrelated. The simplest example of this is the idea comes from the disclaimer, batteries not included. When purchasing a new toy, the price of batteries will not be included in your cognitive price. However, they do increase the overall cost of the purchase. Although it’s a simple example, all-in behaviour is part of all kinds of purchases. For example, gift wrap for presents, ink for your new printer, or upgrades on your newly purchased home. Marketers often leverage this behaviour through simple cues such as showing you “items frequently bought together”.

When mentally adjusting your bank balance, these add-ons won’t be cognitively associated with the cost of the item, which creates a blind spot. This blind spot can cause you to overspend, while simultaneously making you feel good about the purchase due to the additional costs making it better (e.g. renovation, gift wrap, etc.) or functional (e.g. batteries, ink cartridge, etc.).

See a muffin, buy a muffin

Willpower operates like a muscle, and tasks that require self-control can over-exert and weaken it. Distraction is a way that your mental energy can be depleted, making it harder to control impulses. When shopping, your brain is forced to make hundreds of rapid-fire decisions, while trying to resist distractions that you may not even consciously notice. As your pool of willpower depletes, your brain has to work harder and harder to maintain concentration. Something as simple as texting while in line to order a coffee increases your chances of upgrading or buying something extra. Overall, your brain becomes unable to keep up with external stimuli. So, if you see something you want, you’re more likely to buy it, even if it pushes you over budget.

Limit 12 per customer

When the public sees a sign indicting a purchase limit, most conclude that the limit is there to protect the store inventory from being monopolized by a few over-eager bargain hunters. However, this limit is actually a direct marketing attempt at anchoring - the tendency to use irrelevant information as a reference point for estimating value or making financial decisions.

Studies show that signs attempting to illicit anchoring from their customers can increase sales. For example, a field study advertised Campbell’s soup at 79 cents per can with a ‘limit 12 per customer” sign. Shoppers who bought from a display with no limit purchased an average of 3.3 cans. However, buyers who bought from a display with a limit purchased an average of 7 cans. The brain unconsciously anchors with the number 12 and adjusts, resulting in overspending


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Patel, N. (n.d.). 15 Persuasion Lessons You Can Learn From Amazon’s Upsell Strategy. Neil Patel Digital. URL

Wansink, B., Robert, J. K. & Hoch, S. J. (1998). An Anchoring and Adjustment Model of Purchase Quantity Decisions. Journal of Marketing Research, 35(1), 71-81. URL