Consumers used their credit and debit cards more slowly in May but still used them more than they had in May 2010, according to First Data's most recent analysis of consumer card use.

"Card spending growth slowed in May," said Silvio Tavares, division manager of First Data Information and Analytics Solutions, commenting on the card processor's May SpendTrend data. "High gas prices and stubbornly high unemployment constrained growth in most merchant categories."

SpendTrend tracks same-store consumer spending by credit, signature debit, PIN debit, EBT cards and checks at U.S. merchant locations.

The processor reported that higher unemployment and weaker economic conditions negatively impacted consumer spending in May. Year-over-year dollar volume growth slowed to 6.6%, the lowest monthly growth rate in 2011. Year-over-year transaction growth of 5.1% represented the slowest growth over the past 12 months, First Data reported, adding that average ticket values increased 1.4% year-over-year in May, a slight uptick from April and the largest increase in over a year.

“Excluding gasoline stations, average tickets increased 0.5%. Most industries except food/beverage stores and food services/drinking places saw increased average tickets,” the processor reported.