Channels can vary from one another in many ways. In strategic terms,
one of the most crucial is probably the degree to which they engage the
audience member in the actual processing of the information they transmit.
As early landmark research by Herbert Krugman (much of it compiled in
an anthology by his son, Edward P. Krugman, 2008) demonstrated, some
channels permit, or even require, the active psychological involvement of
the audience member in the communication process, while others rely on
audience passivity. Krugman was a researcher with General Electric who
had an interest in advertising. In a series of experiments in the 1960s and
1970s, he measured human responses to communication using such indicators
as brain wave activity and galvanic skin response (changes in the level
of electrical resistance of the skin), interpreting greater volatility in each
instance as indicative of a higher order of psychological involvement in the
processing of incoming information. The 1960s being the age of Marshall
McLuhan, who argued that media varied in their “temperature”—with
so-called “hot” media being more intensely interactive than so-called “cool”
media—Krugman set about the systematic comparison of television
viewing and reading. He found consistently that television viewing, then