Washington, Feb 18 : Consumers often plan to buy unplanned items when they go shopping, a new study claims.

Authors Karen M. Stilley and Jeffrey Inman insist that people often have mental budgets prepared for unplanned purchases.

The authors call the phenomenon ''in-store slack''.

As part of their study the researchers quizzed shoppers at several grocery stores in Texas.

The people were asked what items they planned to purchase, how much they expected to spend on the planned items, and how much they expected to spend on the total trip.

After shopping, participants provided their receipts and answered questions about themselves and the experience.

It was found that more than three-fourths of the participants included room for unplanned purchases.

The authors said: "Shoppers in the study indicated that they employ this strategy both because they anticipate ''forgotten needs'' as well as because they realize that they will encounter ''unplanned wants''-with some respondents even explicitly indicating that they expected to make impulse purchases."

The authors explained that in-store slack leads to overspending, which can disturb the budget of a household.

The researchers wrote: "Less-impulsive individuals who shop most aisles tend to spend the money available from in-store slack, but don''t exceed their overall budgets. In contrast, in-store slack leads to overspending for highly impulsive individuals who shop most aisles.

"For the majority of consumers, having in-store slack appears to be a rational way to use the store to cue needs and preserve self-control. Highly impulsive individuals may want to consider planning as many purchases in advance as possible."

The study has been published in the Journal of Consumer Research. (ANI)