This research demonstrates that the physical properties of shopping carts influence purchasing and spending. Surprisingly, standard shopping carts may reduce spending, because pushing reduces purchasing.

1. Getting a Handle on Sales
Shopping Carts Affect Purchasing by Activating Arm Muscles
From: Estes and Streicher (2022)

2. The Marketing Problem
1. Standard shopping carts are pushed via a
horizontal handlebar
2. Pushing a horizontal handlebar activates the
triceps muscles
3. Triceps activation is associated with avoiding
negative stimuli (e.g., pushing, holding, or
throwing something away from the body)
Therefore, standard shopping carts may be
suboptimal for stimulating purchases.
From: Estes and Streicher (2022)

3. The Marketing Solution
• Biceps activation is associated with approaching
positive stimuli (e.g., pulling or holding
something near the body; bringing food or drink
to the mouth)
Therefore, a shopping cart that activates the
biceps may increase purchasing.
• We designed and patented a new shopping cart
with parallel handles, shown here. We predicted
that these handles would activate the biceps
and hence increase purchasing and spending.
From: Estes and Streicher (2022)

4. We recorded participants’ muscle activity (biceps
and triceps) while they pushed shopping carts
with a horizontal handlebar or parallel handles.
From: Estes and Streicher (2022)
Horizontal Parallel
Electromyography (EMG)
The horizontal handlebar strongly activated the
triceps, whereas the parallel handles strongly
activated the biceps.
0
5
10
15
20
25
30
35
40
45
Horizontal Parallel
Muscle
Activation
(mV)
Triceps Biceps

5. As shoppers entered a supermarket, we randomly gave them either a standard cart with a horizontal
handlebar or a cart with parallel handles. Unbeknownst to the shoppers, as they checked out, the
cashier recorded which shopping cart they had used. Shoppers purchased significantly more
products and spent significantly more money with parallel handles.
From: Estes and Streicher (2022)
Supermarket Experiment
13.79 17.42
0
5
10
15
20
Horizontal Parallel
Products
Purchased
25.97 34.62
0
5
10
15
20
25
30
35
40
Horizontal Parallel
Money
Spent
(€)

6.  For retailers, these results mean missed sales and profits. Retailers could
increase sales by using shopping carts with parallel handles.
 For the majority of consumers, who face a constant battle against over-spending
and over-consumption, standard shopping carts may act as a welcome and
unexpected restraint on buying and spending.
 On the other hand, consumers who want to minimize their shopping trips by
purchasing many products at once may benefit from shopping with parallel
handles.
From: Estes and Streicher (2022)
Practical Implications