It probably won't strike you as the most surprising news of the decade that some brokers have no hearts. But, for an increasing number of investors, their chief source of financial information these days has no flesh, blood or bones, either. In fact, it's wholly electronic.

In the wake of the October 19 market shock, investors have developed even more than their usual distrust of what passes for advice at most brokerage firms. But the investors' need for prompt, reliable financial information seems, if anything, to have increased, and the result has been a surge of products aimed at making the individual more competitive with professional traders.The most obvious usage has been by individuals receiving instant stock quotations on their home computers or on portable, calculator-sized receivers. In addition, more than 300 software packages are now being marketed to help serious investors organize and manage their holdings.

Such devices don't obviate the ultimate need for a broker to execute the transactions, but these investors typically save on commissions by using a discounter, rather than a "full-service" firm, and that means smaller commissions.

While some of the marketing suggests that such investment aids may be for just about everybody, in fact they are aimed at the heavy hitters among individual investors. Computerized Investor, a California-based operation that provides a guide to personal investing by computer, says the software is primarily for those maintaining portfolios of $200,000 or more. Lotus, a major marketer of instant-quote services, figures most of its customers actively trade at least $30,000 worth of securities yearly.

But the day of electronic tools for the masses may be just around the corner. Ethel Daley, senior vice president of Schwab Investor Information Services, estimates that in 10 years at least 30 percent of Schwab's customers - who totaled 1.4 million at the end of 1987 - will do business exclusively by electronic means. "Over 20,000 customers are already using our on-line trading application," she notes.

Computer Investor figures that more than 2 million of the nation's 40-million-plus investors own personal computers, and that there has been a notably rising trend of private investors using them to get up-to-the-second stock quotes and other data without going through a broker.

Unlike the day traders of the past, who sat in brokerage offices all day to complete their in-and-out trades, these new-style investors often work at home and get in and out of positions within minutes.

The trend is a delight to outfits like York Securities, a small New York discounter, which reports that it has about 250 such day traders among its customers, some of whom make 10 trades a day of 1,000 to 5,000 shares each and, the firm says, can turn a profit on a stock gain of as little as an eighth or a quarter of a dollar.

Among the software suppliers of real-time information to individuals are Lotus Development Corp., Telemet America, CMQ Communications, Bonneville Telecommunications, CQI, Data Broadcast Corp. and PC Quote Inc. Leading companies that focus more on brokerage offices include Citicorp's Quotron, ADP, Knight-Ritter and Reuters.

The at-home trader can get information in various ways, from dialing up an information service for quotes to hooking up his personal computer to a device that receives data from coded FM airwaves and then shows quotes instantly on the computer screen.

As Doug Smith, general manager of Lotus Signal's Lotus Information Network, put it to me, "Increasing numbers of investors and traders are realizing that receiving accurate financial market data in a matter of seconds gives them the competitive edge they need to trade more profitably in today's fast-moving market. The personal computer offers the private investor a comprehensive system to analyze individual securities and immediately pinpoint those with the greatest profit potential."

Obviously, the new techniques carry no guarantees of financial success - and, as of now, they aren't for Aunt Sally - or any investor who wants more intermediary hand-holding. But, with at least three leading discounters already allowing customers to enter trades via their home computers, the day may be approaching when disappointed investors will have to blame their failures not on their brokers but on their software.