NEW YORK — With the summer vacation season fast approaching, almost half of Americans (47 percent) say they have already cut back or cancelled vacation plans due to high gas prices, and 20 percent have scaled back their plans because of high air fares, according to this month’s RBC Consumer Outlook Index. The Index for May fell to 42.9, down 1.9 points from April’s 44.8 reading.

Soaring gas prices have already caused three in 10 consumers to reduce their discretionary spending, according to the survey. With the current average price per gallon of gas at $3.90 nationally when this poll was conducted from April 28-May 1*, another 41 percent said they would reduce spending when gas prices climbed above $4.50 per gallon and one in five said their pain threshold was $5 per gallon or more. Asked the same question in March, when the average price for gas was about $3.20 per gallon, half of consumers (50 percent) reported that their threshold for scaling back spending was below $4 per gallon and 20 percent said it was $4.50 per gallon. This data is consistent with numbers published by other research outlets in recent weeks.

“With gasoline price increases showing little sign of abating, this month we asked once again how this impacts discretionary spending,” said Tom Porcelli, chief U.S. economist at RBC Capital Markets. “The results highlight the psychological element involved with rising gasoline prices, as people revise their pain threshold according to the reality of what is happening at the pump. This suggests that, despite what is likely to be a continued drift higher in gasoline prices given supply and demand dynamics, spending is very likely to hold up.”

This month’s decline in the RBC Consumer Outlook Index is driven by all four sub-indices (Current Conditions, Expectations, Investments and Jobs). Seven in 10 Americans say the country is on the wrong track, compared to 30 percent who say it is headed in the right direction. The “wrong track” number is at the highest level observed since 2009, RBC noted.

“Consumer confidence remains fragile, as evidenced by the broad-based decline in the RBC Consumer Outlook Index – indeed, all sub-indices posted declines this month,” added Porcelli. “But what a consumer says can sometimes be at odds with what a consumer does. Confidence fell, but weekly measures of consumer spending remain fairly buoyant and, from our perspective, the second quarter is looking very much like the first quarter. In other words, consumption is not losing momentum.”

*RBC notes that the survey was completed immediately before the news on Osama bin Laden’s death, and therefore does not reflect the impact of that news.