Skinner's experimental work had some lasting merits. He was among the
rewarding of all correct responses. Humphreys [13] then showed that
is withheld, than the rat trained by the consistent-reward method. From
by expectancy -- a step which Skinner never took.
In Hull's case the 'softening-up' process took a different course. In
'appetite'). These secondary drives he saw manifested in anticipatory
antedating goal-stimuli Sg. 'The fractional antedating reaction (Rg)
which constitutes the highest attainment of organic evolution. Indeed
From a strictly logical point of view, the postulate makes no sense --
as Hilgard has pointed out in a careful analysis -- because Sg acts
at the same time as a
producer
of the secondary drive Sd and
as a secondary reinforcer which
reduces
Sd. [15] Hilgard put
down this confusion as a sign of logical weakness in Hull;* yet he
did not seem to realize that Hull was intuitively on the right track,
that the contradiction is merely an apparent one, and vanishes if one
stops thinking in terms of need-reducing motivation. 'That stimulus
associated with reinforcement could become at once
both
a drive and
a reinforcing agent'
sounds
like a contradiction, but makes eminent
sense if, getting rid of the dreadful terminology, we translate it as
follows: 'A rewarding experience can at the same time be both an incentive
and a reward'; or even simpler: 'Some pursuits are self-rewarding'. That
is the implied conclusion of Hull's eighth and last postulate which he
regarded as the crowning achievement of his system. That he himself did
not realize this implication only shows that the once useful S.-R. formula
had by that time become a strait-jacket to thought.
Hunger, Fear, and Curiosity
It took natural philosophy nearly a thousand years to rediscover that
the earth is round; it took experimental psychology nearly fifty years
to rediscover, after its Dark Ages of need-reducing S.-R. theories, that
rats and men are pleasure-seeking creatures, that some activities are
pleasurably self-rewarding, and that exploring the environment, solving a
chess problem, or learning to play the guitar are among these activities.
An interesting reflection on the spirit of the times was the long,
impassioned controversy which followed the earth-shaking discovery that
rats who were allowed to familiarize themselves with the maze by running
around in it without reward, got quicker to the food-box when this was
eventually put in than the control rats who ran the maze for the first
time. How could the rat profit from its previous experience in the maze
without being rewarded by food or punished by electric shock? As Berlyne
put it: 'There are plenty of experiments to show that latent maze-learning
can occur in the rat, which is embarrassing for those whose theories are
not built to assintilate it. . . . Where does the reinforcement for these
responses come from? Several writers have considered the possibility that
it comes from the reduction of curiosity.' [16] Other writers suggested
that it came from the drive-reducing diminution of boredom. One might
as well say that composing a song is a silence-reducing activity.
There have been throughout these Dark Ages 'voices crying in the
wilderness', but they were dismissed as old-fashioned. Thus McDougall
(1923) kept reaffirming that the earth was round and that striving
towards a goal was often more satisfactory than reaching it. Allport
held that activities originally derived from biological needs may
become autonomous and self-rewarding: 'The characteristic feature of
such striving is its resistance to equilibrium: tension is maintained
rather than reduced.' [17] Goldstein emphasized the tendency of organisms
towards 'self-actualization' [18] But the revival of a dynamic psychology
which reinstated the academic respectability of such terms as curiosity,
exploratory drive, purpose, only came about when experimental evidence
showed that even in the rat the urge to explore may prevail over hunger
and fear.
The experiments of Harlow, Montgomery, Butler, Hudson, etc., on rats and
monkeys showed -- what naturalists had always known -- that animals are
inquisitive, that they have an urge to manipulate, explore, to 'look
what's inside', which is independent from such biological drives as
hunger, sex, and fear -- or, rather, that the exploratory drive itself
stems from a primary biological need. They showed that exploratory
behaviour may combine with, or enter the service of, hunger or fear, but
that it may also compete with and sometimes assert itself against them;
and that novelty, surprisingness, or puzzlement are as real incentives
to learning as pellets of food dropped into the Skinner box. [19]
As far back as 1930 Nissen had found that rats would cross an electrified
grill to reach a maze which contained nothing but some unusual objects;
he concluded that an exploratory urge did exist -- 'a biogenic drive to
explore, perceive, to know'. [20] Experiments by Hudson, Berlyne, and
Walley, in which rats were punished for approaching some novel visual
pattern, led them to conclude that 'objects that have become associated
with danger are often explored before they are shunned'. [21] Carr and
Williams [22] showed that the exploratory drive varies with heredity and
environment: hooded rats explore more than black rats, and black rats more
than Albino rats. Montgomery and Barnett [23] showed that wild rats are
more frightened, tame rats more attracted by novelty; Thompson and Heron
[24] that young animals are more curious than old ones, and -- as one
would expect -- that female rats are more inquisitive than males. [25]
Confronted with novel situations, hungry rats interrupt their feeding
to explore their surroundings; [26] but rats whose cerebral cortex
has been removed in part, while still capable of learning to run a
maze to get at food, show a diminished tendency to exploration. They
'do not evince the preference for a variable path over a standardized
path that is characteristic of a normal rat, except when the variable
path is the shorter. Brain-damaged rats likewise show less variability
of route in a Dashiell maze.' [27] Yet, as Lashley's rats have shown,
even depriving the creature of substantial portions of its brain does
not make it conform to the S.-R. ideal.
On higher levels of the animal kingdom the evidence becomes less
monotonous and depressing. What a relief to get out of the Skinner box
and to read Lorenz's description of curiosity battling with fear in one
of his birds: [28]
A young raven, confronted with a new object, which may be a camera,
an old bottle, a stuffed polecat, or anything else first reacts with
escape responses. He will fly up to an elevated perch and, from this
point of vantage, stare at the object literally for hours. After this,
he will begin to approach the object very gradually, maintaining all
the while a maximum of caution and the expressive attitude of intense
fear. He will cover the last distance from the object hopping sideways
with half-raised wings, in the utmost readiness to flee. At last,
he will 'deliver a single fearful blow with his powerful beak at the
object and forthwith fly back to his safe perch. . . .' In the end
'he will grab [the object] with one foot, peck at it, try to tear 'off
pieces, insert his bill into any existing cleft and then pry apart
his mandibles with considerable force. Finally, if the object is not
too big the raven will carry it away, push it into a convenient hole
and cover it with some inconspicuous material.
As for primates, we can comfortably fall back on Darwin's
Descent of
Man
:
All animals feel Wonder, and many exhibit Curiosity. They
sometimes suffer from this latter quality, as when the hunter plays
antics and thus attracts them; I have witnessed this with deer, and so
it is with the wary chamois, and with some kinds of wild-ducks. Brehm
gives a curious account of the instinctive dread, which his monkeys
exhibited, for snakes; but their curiosity was so great that they
could not desist from occasionally satiating their horror in a most
human fashion, by lifting up the lid of the box in which the snakes
were kept.
Darwin was 'so much surprised at this account' that he proceeded to
the monkey-house at the Zoological Gardens armed with a stuffed snake,
a dead fish, a mouse, and a live turtle:
The excitement thus caused was one of the most curious spectacles
which I ever beheld.' The greatest success was the turtle. The monkeys
'showed unbounded astonishment, as well as some fear. . . . This was
displayed by their remaining motionless, staring intently with widely
opened eyes, their eyebrows being often moved up and down. Their faces
seemed somewhat lengthened. They occasionally raised themselves on their
hindlegs to get a better view. They often retreated a few feet, and then
turning their heads over one shoulder, again stared intently. . . . In
the course of a few minutes some of the monkeys ventured to approach
and touch the turtle. . . . I then placed a live snake in a paper bag,
with the mouth loosely closed, in one of the larger compartments. One of
the monkeys immediately approached, cautiously opened the bag a little,
peeped in, and instantly dashed away. Then I witnessed what Brehm has
described, for monkey after monkey, with head raised high and turned
on one side, could not resist taking a momentary peep into the upright
bag, at the dreadful object lying quietly at the bottom. [29]
This was written half a century before Köhler's
Mentality of
Apes
was translated into English -- with a delay of eight years
after the appearance of the German original. [30] It had the effect of
something like a bombshell on American psychology, in which Pavlov and
Watson were all the rage. Yet even Köhler, though he attacked Thorndike,
remained essentially conservative as far as motivation is concerned;
it took another quarter-century for a new crop of experimentalists to
discover, in the 1950s, that the exploration of novelty, the manipulation
of objects, the dismantling and reassembling of complex manual puzzles,
and even scribbling and drawing were self-rewarding and self-arousing
activities.
'Those who have had opportunities to observe monkeys and apes at
close hand for prolonged periods invariably dwell on their addiction
to looking, mauling, prodding, licking, and generally squeezing every
drop of possible entertainment from whatever crosses their path.' [31]
Particularly revealing is the fact that Rhesus monkeys who have learned
to dismantle a complex manual puzzle of interlocking pieces performed
better when there was no food reward put inside the puzzle than when
they knew that there was one. In the second case they got impatient
and tried short-cuts; in the first case they practised disinterestedly,
'l'art pour l'art'
. [32]
The Exploratory Drive
The cumulative evidence of these and similar experiments led Harlow to
the conclusion:
There are logical reasons why a drive-reduction theory of learning,
a theory which emphasizes the role of internal, physiological-state
motivation is entirely untenable as a motivational theory of learning.
The condition of strong drive is inimical to all but very
limited aspects of learning -- the learning the ways to reduce
tension. . . . The hungry child is a most uncurious child, but after
he has eaten and become thoroughly sated, his curiosity and all the
learned responses associated with his curiosity take place. [33]
Montgomery came to similar conclusions, which he put into the laconic
formula: 'Exploratory behaviour is motivated by the exploratory drive.'
These clarion calls of a new generation of experimentalists in fact
echoed the earher 'voices in the wilderness' -- such as Woodworth's: 'To
see, to hear -- to see clearly, to hear distinctly -- moment by moment,
such concrete, immediate motives dominate the life of relation with the
environment.' [34] In the meantime, however, these 'old-fashioned' views
had received added, powerful support from neurophysiology. Lindsley
(1951), Hebb (1955) and others have shifted their attention from
tension-reducing, stabilizing processes in the nervous system to
the supposedly arousing, attention-sharpening functions of certain
structures in the midbrain -- the so-called 'reticular activating system',
RAS. Although these theories are still controversial, parallel studies on
sensory deprivation have dramatically revealed the deleterious effects
of protracted stimulus-starvation, and the organism's need for more or
less constant stimulation, or at least a steady inflow of information --
a hunger for experience and thirst for excitation probably as basic as
hunger and thirst themselves. Instead of responding passively to the
environment, 'human beings and higher animals spend most of their time
in a state of relatively high arousal and . . . expose themselves to
arousing stimulus situations with great eagerness'. [35] Two thousand
years ago Juvenal had said much the same: 'Duas tantum res anxius optat,
/ Panem et circenses.'
Berlyne [36] has made a systematic survey of the manifestations of
the exploratory drive on various levels -- from orientation reflexes
to artistic and scientific curiosity. At the bottom of the ladder we
have Pavlov's 'investigatory' or 'what is it?' reflex. 'It is this
reflex', Pavlov wrote in a famous passage, 'which brings about the
immediate response in men and animals to the slightest changes in the
world around them, so that they immediately orientate their appropriate
receptor-organ in accordance with the perceptible quality in the agent
bringing about the change, making full investigation of it.' [37] From
true reflexes such as dilatation of the pupil and automatic scanning,
we ascend to oculo-motor responses, movements of the head or the whole
body towards the stimulating phenomenon: animals prick their ears,
tense their muscles, sniff the air 'musingly'. Next comes 'locomotor
exploration' which 'appears to be universal among higher vertebrates
and present to some degree in other branches of the animal kingdom';
yet, as Berlyne ruefully remarks: 'It has been studied systematically in
rather few species. By far the greater part of the relevant literature
is concerned with the rat.' According to Darchen [38], even the cockroach
is capable of disinterested latent learning, prompted by sheer curiosity;
while kittens, puppies, and young chimps seem to spend a major portion of
their time in 'locomotive exploration'. Lastly, we come to 'investigatory'
or 'inquisitive' behaviour, ranging from Darwin's monkey who cannot
refrain from peeping into the snake-infested Pandora's box, to the
'insatiable curiosity' of the artist and explorer.