Major Retailers Note Encouraging Gains : Economy: Initial jobless claims are also down. But a survey of capital spending points to weak growth.

Reports on retail sales, capital spending and new jobless claims painted a mixed picture for the economy Thursday.

Several of the nation’s biggest retailers said they had strong sales gains in May as a spring heat wave sent shoppers in search of summer clothing.

But the figures released by the merchants still left economists wondering whether consumers were responding to signs that the recession might be ending.

Some securities analysts said there were signs from the sales figures that consumers are coming out of their shell.

“We’re starting to get little signals that things are getting better,” said Thomas J. Tashjian, an analyst with First Manhattan Co., a New York investment company.

Tashjian said that store and mall traffic is up and that the size of an average purchase is edging higher.

But Wayne Hood, an analyst with Prudential Securities Inc., said some retailers had a better showing last month “because of favorable weather patterns.”

Discount retailers, including Wal-Mart Stores Inc. and Kmart Corp., were again the industry leaders last month as consumers continued to shop frugally.

Wal-Mart, the nation’s largest retailer, said sales at stores open a year or more rose 13% last month from May, 1990, levels.

Same-store figures, which apply only to locations that have been open at least a year, are regarded as the best indicator of performance than total sales because these normally include new stores.

Kmart reported an 8.5% increase in same store sales, while Sears, Roebuck & Co., recently displaced by Wal-Mart as No. 1, said same-store sales slipped 1.3%. J. C. Penney Co. said its same-store sales fell 2.5%, while Dayton Hudson’s rose 0.8% and May Department Stores Co.’s rose 2.9%.

In a bit of weak economic news, the Commerce Department said a survey conducted in April and May showed that U.S. businesses plan to boost their investment spending by just 3% after inflation, the smallest increase in five years.

A survey of spending plans conducted in April and May showed that companies would boost spending in 1991 by significantly less than the increases of 4.5% after inflation in 1990 and 10.4% in 1989.

Economists said the spending probably will not play a major part in reviving growth. Nonetheless, they said it was good news that companies plan to spend more on new plants and equipment--particularly later in the year.

It would be the poorest performance for plant and equipment spending since 1986, when spending dropped 4.1%.

Spending slowed sharply in the second half of 1990, as the economy slipped into recession.

On the employment front, the government reported that the number of Americans filing new claims for unemployment benefits fell for the third straight week in May, the first such streak of improvements in more than a year.

“It suggests that the new ‘R’ word is recovery, not recession,” said Irwin Kellner, chief economist at Manufacturers Hanover Trust.

“Evidence that the recession is ending is piling up and this adds another block to it,” added Robert Dederick of the Northern Trust Co. of Chicago.

The Labor Department said 439,000 people filed first-time unemployment claims for the week ending May 25, down 6,000 from the previous week’s 445,000.