I have no data, but let me make some off-the-cuff predictions about your plan to create "premium" supermarket checkouts:
Customers who understand your novel scheme will tend to queue up in the line which has the lowest prices, because people do not consciously understand what their time is worth.
Then other customers will see the long line at the discount aisle and subconsciously decide to leave your store without buying, because the lines are too long.
Or perhaps, instead of abandoning their attempt to buy anything, frustrated customers will notice an apparently empty checkout line with a cashier standing there. They'll approach that line, and be told that that it's a "premium lane" which will cost them an extra 5%. Then they will become enraged. Nobody wants to pay extra for a service that they're accustomed to get for free. And when they're told that they can always stand in the long, less expensive line, they will continue to be enraged at the sight of one or more cashiers standing around idle in the premium lane, waiting for premium customers, when those lazy cashiers could be helping out in the discount aisles! What do we pay those bums minimum wage for, anyway?
Inevitably, unless you are on-site breathing down their necks, your cashiers will give in to popular pressure and go to work in the discount lanes. At which point the premium lanes will have no cashiers, and nobody will use them.
Of course, if grocery stores were more like emergency rooms -- scarce, high-margin businesses which routinely force you to wait two to eighteen hours for service -- things might be different.
For info on shopper behavior from a guy who actually does have data, I recommend Paco Underhill's Why We Buy: The Science Of Shopping.
UPDATE: I have the answer! You could invent a scheme where customers who want to avoid waiting in line can trade their own labor for a shorter wait -- by scanning and bagging their own groceries at an automated kiosk. Suddenly, via a series of psychological tricks, your idea works well. I should patent this amazingly original variation of your idea. :)
So re-label it as a discount line. People who are willing to shop at odd hours or are willing to wait during peak times can save 5-10%. Meanwhile mark the rest of your stuff up 5-10%.
Not sure whether people pay enough attention to their grocery bills to tell a 5% increase, but I hear grocery store margins are terrible (like 2-3%) so maybe they would. It's tough to tell without some data.
I agree that the initial response would be something like that, but it is the long-term behavior that I would be interested in.. Do people rationally value their time? Probably not. But I will bet you that some people would be willing to shop in the premium isles.
An automatic kiosk is a way to get around this, except you do extra work instead of paying more. But that misses the whole point of this - it isn't a solution to the lineup problem, it is a social experiment. You could potentially find out how much people value their time, in dollars and cents.
Customers who understand your novel scheme will tend to queue up in the line which has the lowest prices, because people do not consciously understand what their time is worth.
Then other customers will see the long line at the discount aisle and subconsciously decide to leave your store without buying, because the lines are too long.
Or perhaps, instead of abandoning their attempt to buy anything, frustrated customers will notice an apparently empty checkout line with a cashier standing there. They'll approach that line, and be told that that it's a "premium lane" which will cost them an extra 5%. Then they will become enraged. Nobody wants to pay extra for a service that they're accustomed to get for free. And when they're told that they can always stand in the long, less expensive line, they will continue to be enraged at the sight of one or more cashiers standing around idle in the premium lane, waiting for premium customers, when those lazy cashiers could be helping out in the discount aisles! What do we pay those bums minimum wage for, anyway?
Inevitably, unless you are on-site breathing down their necks, your cashiers will give in to popular pressure and go to work in the discount lanes. At which point the premium lanes will have no cashiers, and nobody will use them.
Of course, if grocery stores were more like emergency rooms -- scarce, high-margin businesses which routinely force you to wait two to eighteen hours for service -- things might be different.
For info on shopper behavior from a guy who actually does have data, I recommend Paco Underhill's Why We Buy: The Science Of Shopping.
UPDATE: I have the answer! You could invent a scheme where customers who want to avoid waiting in line can trade their own labor for a shorter wait -- by scanning and bagging their own groceries at an automated kiosk. Suddenly, via a series of psychological tricks, your idea works well. I should patent this amazingly original variation of your idea. :)