LOUDONVILLE — Consumer sentiment is defying the notion that what goes up must come down, as a plurality of New Yorkers expect gasoline and food prices to rise over the second half of 2008, according to a Siena Research Institute survey released Wednesday.

SRI’s poll on the fiscal impacts of gas and food price hikes shows that the hardships they impose on New Yorkers is spreading. Seventy-eight percent of survey respondents in July said gas prices are having a somewhat serious or very serious impact on their finances, up 4 percentage points from the previous month. During the same period, 81 percent of New Yorkers reported taking fiscal hits because of higher grocery bills, a 9 percentage point jump.

“Gas and now food costs are really biting into budgets. These new higher prices hit lower-income people first and hardest, but now wallets of every size are feeling the pinch,” said SRI Founding Director Douglas Lonnstrom.

Over the next six months, 44 percent of New Yorkers said they expect gas prices to rise and 60 percent were bracing for more food price spikes.

Fifty-six percent of New Yorkers said they were very concerned about winter heating costs. The New York State Energy Research and Development Authority is predicting household heating bills to jump almost 150 percent from a year earlier.

Even though the price of crude oil has backed away by almost $30 from its July 11 record high of $147.27 per barrel, only 21 percent of respondents said they have benefited from the lower gas prices caused by oil’s retreat. The price of a regular gallon of gas in the Capital Region Wednesday was $4.02, down 4.5 percent from a month ago but up 34.9 percent from a year ago, according to the AAA Fuel Gauge Report.

Consumers are increasingly coming to expect higher prices on goods and services, partly because increases have been gaining momentum throughout the year. The nation’s inflation rate in June rose 1.1 percent over the month. That was the largest monthly spike since September 2005. May saw a 0.7 percent increase.

The U.S. consumer price index in June was up 5 percent over the previous 12 months — the largest annual spike since 1991, according to the U.S. Department of Labor.