Article fpsyg-09-00373 March 17, 2018 Time: 18:6 # 1
published: 20 March 2018
University of California, Los Angeles,
Universidad de Guadalajara, Mexico
Trinity College, United States
This article was submitted to
Theoretical and Philosophical
a section of the journal
Frontiers in Psychology
Received: 10 August 2017
Accepted: 06 March 2018
Published: 20 March 2018
Overskeid G (2018) Do We Need
the Environment to Explain Operant
Behavior? Front. Psychol. 9:373.
Do We Need the Environment to
Explain Operant Behavior?
Department of Psychology, University of Oslo, Oslo, Norway
By way of operant conditioning, human behavior is continuously shaped and maintained
by its consequences – and understanding this process is important to most fields of
psychology and neuroscience. The role of the learning organism’s environment has long
been contentious, however. Much relevant research is being done by people identifying
with the Skinnerian tradition, who tend to agree that the causes of behavior can be found
exclusively in the environment. The meaning of this proposition is not clear, however.
Some authors say the environment is outside the body, others claim it is also inside it.
Among those who say the environment is outside the body, many are of the opinion that
events inside the body and hence (in their view) not in the environment can also cause
behavior, though they claim that events inside the body cannot be causes in the same
sense as events taking place outside it. This is confusing, and the present paper argues
that the “environment” may neither be a useful nor a necessary concept in the analysis
of behavior. Moreover, abolishing the concept could clear the way for a reintegration of
Skinnerian psychology into the mainstream.
Keywords: environment, cause, B. F. Skinner, behaviorism, prediction, control
B. F. Skinner (e.g., Skinner, 1981) and those working in the Skinnerian tradition have mapped in
great detail how a behavioral repertoire is selected, shaped, and maintained by its consequences.
People’s ability to adapt, often unconsciously, to the situations in which they find themselves is
based on sensitivity to consequences (Pessiglione et al., 2008; Lieberman, 2012) – and if researchers
do not understand how consequences affect behavior, most of what psychology and neuroscience
studies will itself be difficult to understand (e.g., Overskeid, 2000). Human behavior is, after all,
continuously being affected by operant conditioning, which is, of course, what we call the process
by which consequences modify behavior (see Lieberman, 2012).
A wealth of empirical knowledge relevant to operant behavior has long existed, but has not
always been integrated into the theories and empirical studies of mainstream psychologists. This, it
appears, has to do with the relative isolation of “behavior analysts” (see Overskeid, 1995a), the
name often used by those working within the Skinnerian tradition. What, exactly, hinders the
integration of this group of researchers into the psychological mainstream, with the potential for
dialog and renewed attention to important basic phenomena, like learning and conditioning, that
such a development might entail?
RADICAL, YET INCREASINGLY SIMILAR
Behaviorism is more than a century old, though it’s doubtful if anyone now subscribes to the views
of Watson (1913), the movement’s founder. B. F. Skinner’s school of thought is another matter (see
Overskeid et al., 2012). This American iconoclast once planned to make over “the entire field” of
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Overskeid Do We Need the Environment?
psychology “to suit myself ” (Skinner, 1979, p. 38) – and before
the cognitive revolution of the 1950s and ‘60s it may have seemed
as if he was on his way to doing just that (e.g., de Waal, 2017).
Today, Skinnerian thinking is hardly fashionable. Yet even
after his death in 1990, Skinner was still topping a list of
the world’s most eminent psychologists (e.g., Haggbloom et al.,
2002). A very recent study ranked him second (Green and
Martin, 2017). His influence in undeniable, even today, and
those working within the Skinnerian paradigm keep producing
basic and applied research that is often very relevant to the
understanding of operant behavior (e.g., Gomes-Ng et al., 2017;
Johnson et al., 2017).
Skinner called himself a “radical” behaviorist – and as opposed
to other behaviorisms, the Skinnerian brand fully accepts the
existence of private events, like thoughts and feelings. Indeed,
Skinner (1974, p. 212) stated: “What is inside the skin, and
how do we know about it? The answer is, I believe, the heart
of radical behaviorism.” In practice, this has led to cognitive
and behaviorist tactics of research becoming increasingly similar
when the two schools attack the same problems (see Overskeid,
1995b). However, they do not often work on the same problems.
Why is this?
There is no doubt that radical behaviorists tend to see themselves
as separate from mainstream psychology (Pietras et al., 2013),
some even arguing that what they are doing is a separate science,
no longer psychology (Vargas, 2017).
What is the basic difference, then, that separates today’s
Skinnerian behaviorism from psychology as most psychologists
see it – and which still makes it meaningful to speak of a
separate school of thought? To Skinner, the assumption was
central that the causes of behavior are always to be found in the
environment. And Skinner (1984, p. 719) pointed to his “central
position” as a reason why psychologists often did not follow his
reasoning. “To move from an inner determination of behavior to
an environmental determination is a difficult step,” he concluded
(Skinner, 1984, p. 719).
Skinner, it seems, hit the nail on its head. The belief in
“environmental determination” does indeed appear to be the
main theoretical reason why behavior analysis stands apart from
mainstream psychology (e.g., Overskeid, 2006), and some have
argued that this view of causation is the reason why behavior
analysts have been successful in reaching their goals (e.g., Pietras
et al., 2013).
So what, then, is the “environment” in behavior analytic
theory? What does it determine? And does the belief in
environmental determination really hinder the integration of
behavior analysis into mainstream psychology?
PREDICTION AND CONTROL
From its inception, the behaviorist movement has strived to
achieve prediction and control of behavior. Watson (1913) was
the first to state these goals, and Skinner (e.g., Skinner, 1953)
affirmed them. Some behavior analysts prefer “influence” to
the word “control” (e.g., Hayes et al., 2013). Skinner, on the
other hand, sometimes used a stronger expression, and spoke
of “total control” of operant behavior (Skinner, 1986, p. 232).
Be the slightly different formulations as they may, the tenet that
prediction and control is its purpose “runs through the behavior
analytic literature” (Bach and Moran, 2008, p. 18).
The usefulness of an element in a theory, an explanation,
or an assumption, must be gaged by the extent to which the
element contributes to the attainment of goals – in the case of
behavior analysis, prediction and control. At issue, then, is what
the concept of the environment can do to help behavior analysts
reach their goals.
ENVIRONMENT AND CAUSES
The environment has been a central concept in behavior analysis.
In an oft-quoted passage, Skinner (1957, p. 1) depicts the essence
of what behavior analysts analyze: “Men act upon the world,
and change it, and are changed in turn by the consequences
of their action.” This quotation from Skinner (1957) illustrates
that operant behavior is part of a chain of events with no clear
beginning or end. Hence those wanting to understand behavior
must make certain decisions as to which events should be called
“causes,” thus marking them as especially relevant to an analysis
having prediction and control as its final goal.
Skinner saw that causes of behavior, that is, events that are
not only sine qua non, but also especially relevant to prediction
and control, can be found inside as well as outside the body.
Indeed, he often emphasized that variations in ease of observation
do not create differences in status that are important to the
analysis of behavior and its causes. Indeed, “The skin is not that
important a boundary. Private and public events have the same
kinds of physical dimensions,” said Skinner (1963, p. 953), who
was himself a pioneer in the experimental investigation of private
events (e.g., Heron and Skinner, 1937).
And in an authoritative exposition of Skinnerian thinking,
Delprato and Midgley (1992, p. 1512) concluded: “Private events
refer to ‘real’ events, and their ontological status is identical
to that of any other aspect of the physical world.” If this
interpretation is correct, since private events are identical to other
aspects of the world, it should follow that private events can
also be causes of behavior, with the same status as any other
class of events. Skinner sometimes appears to adopt this view in
his theoretical analyses. He says, for instance, that a man may
“state his intention,” and explains that “once such a statement
has been made, it may well determine action as a sort of self-
constructed rule. It is then a true precursor having an obvious
effect on subsequent behavior. When it is covert it may be hard to
spot; but it is still a form of behavior…” (Skinner, 1969, p. 126).
At other times, Skinner’s appeal to inner causation is by way of
illustrations or examples, in which private events more than once
are given the status of causes of behavior (for examples, see Zuriff,
1979; Overskeid, 1994). Skinner did make a distinction, however,
between causal events that can be observed by more than one
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individual, and those that are only accessible to the acting
person, stating that “private events… may be called causes, but
not initiating causes” (Skinner, 1984, p. 719). Behavior analysts
appear to agree on this (e.g., Catania, 1988; Pierce and Cheney,
“Initiating cause” is a term that has been used in many areas of
research. If an event in a causal chain can be deemed unusual or
conspicuous, and has also appeared relatively close in time to the
event to be explained, it is often given the name of an initiating
cause (e.g., Sydora et al., 2003; da Silva et al., 2004; Steine et al.,
2011). The difference between an ordinary cause and a cause that
is not “initiating” has never been fully explained, however (but see
Flora and Kestner, 1995, and Overskeid, 2006, for an exchange of
views). As regards the present discussion, the important thing is
that Skinner clearly, at least from the publication of Science and
Human Behavior (Skinner, 1953) onwards, saw private events as
potential causes of behavior – though not of the initiating type.
Private events, according to Skinner, can serve as discriminative
stimuli, as well as punishing and reinforcing consequences (for
examples, see below, and also Zuriff, 1979; Overskeid, 1994).
THE ROLE OF THE ENVIRONMENT
We shall not spend more time discussing external and internal
causation per se, that has been done elsewhere (e.g., Staddon,
1973; Smith, 1987; Overskeid, 2012). The question is important,
however, because it leads directly to the role of the environment
in behavior analysis. The environment’s centrality has perhaps
been taken for granted, which may be the reason why the
concept’s usefulness has hardly been debated – but we shall see
that, given the way it has been used by behavior analysts, it
may not always be easy to pinpoint the meaning of the word
An influential textbook has defined behavior analysis as
“the science that studies environmental events that change
behavior” (Miller, 2006, p. 5), before going on to explain that
“environmental events are any events outside the person.” This
may seem entirely reasonable.
Moreover, Skinner appears to agree. In psychology, he
explained (Skinner, 1974), several schools of thought have
assumed that the environment can exist within a person. The
way these schools saw it, “[a] part of the environment entered
the body,” said Skinner (1974, p. 73), “was transformed there,
perhaps was stored, and eventually emerged as a response.” But
behavior analysts, Skinner explained, see this differently: “In an
operant analysis, and in the radical behaviorism built upon it,
the environment stays where it is and where it has always been —
outside the body” (Skinner, 1974, p. 73, italics in original).
The Skinnerian point of view is clear, then. Yet it might still
lead to difficulties if we consider, for example, the way humans
typically perceive their surroundings. Skinner (1953) illustrates
this well in his treatment of what he calls the “interpreted”
stimulus. A man may think, for instance, that he has found his
coat on the coat rack in a restaurant — and given that this is his
interpretation of a stimulus, he may start examining the contents
of the coat’s pockets, which he would not otherwise have done.
Or a person may observe a faint haze at the edge of a forest, and
consider whether it is fog or smoke. “[I]n one case we simply
pass on; in the other we dash to give the alarm. We may do
neither until we have ‘decided which it really is.’ We ‘interpret’ the
stimulus before taking specific overt action,” says Skinner (1953,
There are, as we saw, many similar examples in Skinner’s
writings, but those mentioned here should suffice to show
that Miller’s (2006) way of defining “environmental events”
and “behavior analysis” runs into difficulties. Though his
description of the environment is in agreement with Miller’s,
Skinner also describes how responding can be strongly affected
by interpretations and other private events — indeed, our
interpretation of a stimulus can decide whether we do nothing,
or whether we “dash to give the alarm” (Skinner, 1953, p. 139).
The interpretation, then, may seem more “initiating” than the
external stimulus, described by Skinner (1953, p. 139) as “a faint
haze” which in itself does not occasion behavior.
If what Skinner is doing is behavior analysis, these examples
alone should show that behavior analysis deals with events that
change behavior even if they occur inside a person. Hence Miller
(2006) seems to have a problem.
OUTSIDE OF BEHAVIOR?
A possible solution to Miller’s (2006) predicament is that of
Lokke et al. (2011). As opposed to Skinner (1974), they state
that seeing the environment solely as existing outside the body
is not in keeping with modern behavior analysis, and argue that
stimulation from the body as well as consequences within the
body are often involved in functional explanations of behavior.
It is more precise, say Lokke et al. (2011) to think of the
environment as existing outside of behavior, but not necessarily
outside the body.
But is this really a solution to our quandary? How easy is it to
draw a line between environment and behavior? Can such a line
be clearly drawn at all — especially given the fact that behavior
analysts typically see behavior as “anything an organism does,” in
the words of Catania (1992, p. 364)? Catania goes on to explain
that covert behavior is also behavior, and specifies, for instance,
that “a shift of attention need not involve eye movements but
qualifies as behavior” (Catania, 1992, p. 364).
It is not a controversial assumption that behavior can itself
function as discriminative stimuli (e.g., Catania, 1992). Overt
behavior can serve this function (e.g., Guerin, 1992), and also
private events, as we saw above, as when, for instance, the
behavior of interpretation becomes a discriminative stimulus.
Skinner (1969) gives many more examples of private rules serving
as discriminative stimuli.
It is also well documented that engaging in certain behaviors
can function as reinforcement, Premack’s studies (e.g., Premack,
1962) being the most well known demonstrations (see Killeen,
2014, for a more recent discussion of the Premack work). In
his 1962 article, Premack concluded (p. 257): “… it was possible
not only to reinforce drinking with running, but also to reverse
the reinforcement relation in the same subjects…” Zuriff (1979)
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has an interesting discussion of the several types of covert
behaviors that according to Skinner can serve as reinforcement
Discriminative and reinforcing stimuli are often seen as being
part of the environment, and it is true that they often exist outside
the body as well as outside of behavior. It is difficult to claim,
however, that this is always the case. Indeed, there is every reason
to assume that human behavior is quite frequently under the
control of stimuli that are themselves behavior, as when I run
because I believe I’m late, and the behavior of running is caused
by the behavior of believing. Let’s not quarrel about the exact
causal status of believing in this example. Whether one wants to
call it an initiating cause or not, it is a cause, and being a behavior,
it cannot at the same time be said to exist “outside” of behavior.
Another example: A boy’s doing his homework is reinforced
by his parents allowing him to play computer games. The
reinforcer, then, is at the same time a behavior, and again
something that cannot be said to exist outside of behavior.
If we say that discriminative and reinforcing stimuli are part
of the environment, it is not obvious, in other words, that the
concept of the “environment” is made more useful by defining
it as events taking place outside behavior rather than outside the
It may seem, then, that we are left with two alternatives. The
first would be to stick with Skinner’s (1974) and Miller’s (2006)
standpoints. However, if the environment exists only outside
the body and behavior analysis studies only the effects of
environmental events, it is difficult to see how behavior analysis
can study covert behaviors like rule following and emotions –
even though Skinner (1974) told us above that the what happens
inside the skin is the heart of radical behaviorism.
Private rules, for instance, the way Skinner (e.g., Skinner,
1969) saw them, are clearly causes of other behavior (though in
his view not “initiating”) — and even a well-known cognitive
psychologist has seen Skinner’s theory of rules as “an ingenious
analysis” (Sternberg, 1984, p. 605). The second alternative, then,
could be to agree with those, including Lokke et al. (2011) who
argue that the environment can be inside us – but as we saw
above, this, too, may lead to trouble.
A discussion may be needed, then. Do we need to choose
between the two alternatives? Should we find a third? Or
perhaps one should try to base the behavior analytic search
for causes simply on stimuli, the most important being those
of the discriminative and reinforcing kind, without necessarily
appealing to the environment – a concept that might be
It’s not obvious, after all, that prediction and control of
behavior is always made easier by including the concept of the
environment in any analysis. The discussion above may indicate,
instead, that using the word can complicate things. “The point
is,” said Staddon (1993, p. 446), “that the environment-based
versus organism-based distinction is often impossible to make in
As opposed to the environment, it is uncontroversial among
Skinnerians that stimuli can occur inside the body. The stimuli
that give rise to seeing are good illustration, as in “Seeing does
not require something seen,” Skinner’s famous dictum – after
which he continued: “We acquire the behavior of seeing under
stimulation from actual objects, but it may occur in the absence
of these objects under the control of other variables” (Skinner,
1963, p. 955). “Other variables” are not necessarily outside the
body. Indeed, if we close our eyes, and still see an object, our
seeing must necessarily occur in the absence of actual objects, and
must therefore be occasioned by private stimulation (see Skinner,
WHAT IS A PRIVATE EVENT?
In behavior analytic terminology, a stimulus or a response is
private or covert when it is accessible only to the person whose
behavior it affects (if a stimulus) or whose behavior it is (if
a response). For stimuli or responses to escape the fate of
being called covert, many types of observation appear acceptable,
however. A machine can register a rat’s lever pressing, and even
if no one watched the rat in its experimental chamber, we regard
the machine’s registration as evidence that the behavior has taken
place, and do not call it a private event. A fish may swim around
in a pond inside a cave that cannot be accessed by humans. We
can get a camera into the pond, however, and even though we
need the aid of machinery to observe the swimming fish, we do
not call its swimming a covert response.
There are now more ways than ever in which machinery can
blur the line between public and private, and Skinner pointed
out (Skinner, 1989, p. 18) that “[t]here are two unavoidable gaps
in any behavioral account: one between the stimulating action
of the environment and the response of the organism and one
between consequences and the resulting change in behavior. Only
brain science can fill those gaps.” Since computer programs using
data from brain imaging can now reliably decode things people
imagine, intend, and remember (see Smith, 2013), it is getting
more difficult, in many instances, to see the difference between
public and private events.
As technology continues to advance, it should become
increasingly easy to study more directly the private events that
radical behaviorists already see not only as real, but even as
important aspects of human behavior (e.g., Skinner, 1974). Brain
science has come, in other words, some way toward filling
the gaps that Skinner (1989) described. Furthermore, improved
access to neural processes may weaken the distinction between
public and private events, which could make it less meaningful
to differentiate between events taking place in or outside the
environment. Indeed, “the skin is not that important a boundary,”
we saw Skinner pointing out as early as 1963 (p. 953).
It does not seem obvious that ascribing all causes of behavior
to the environment can always help behavior analysts get closer
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to their goals of prediction and control. Indeed, it is not
always obvious what the “environment” refers to in behavior
analytic terminology, and whether applying the term can make
explanations and hypotheses any clearer. It may be the case,
however, that including the “environment” in behavior analytic
hypotheses or explanations can sometimes hinder prediction and
control. There are two main reasons for this.
First, scientists continue to prefer the simplest explanation
that is consistent with existing data (e.g., Gauch, 2003) – whether
it be based on simple hypotheses’ greater amenability to testing
(see Baker, 2010), or on an assumption that simpler hypotheses
have, other things equal, a greater probability of being true
(Jefferys and Berger, 1992; Swinburne, 1997). We have seen that
if the concept of stimulus is used in an analysis of behavior,
introducing the term “environment” is sometimes – perhaps
always – superfluous, and therefore contrary to the scientific ideal
Second, if the environment is taken to be the abode of
the only stimuli that can initiate responding, this could make
researchers look for causes only in those places they regard as
parts of the environment – thus running the risk of ending up
by manipulating stimuli that do not change behavior in the most
efficient manner. It is worth remembering that Skinner (1953,
1969) described how a person’s interpretations, intentions, and
other rules can affect his or her behavior in important ways –
even if, by some definitions, such private events are not initiating
When private events are important determinants of behavior,
it can sometimes be a mistake not to focus primarily on changing
those events if the goal is to change the way a person acts. After all,
my interpretation of a stimulus can decide if I raise the alarm or
do nothing, and following a rule can even make operant behavior
insensitive to consequences (e.g., Hayes et al., 1986).
The concept of stimuli – discriminative, reinforcing, or
otherwise, is of course as important as always. But causes are
everywhere, and their importance does not always depend on
their visibility or where they are to be found. It is clearly possible
to speak of causes simply in terms of stimuli, and it is not
clear that anything would be lost if one stopped referring to the
Mainstream psychologists believe that thoughts and feelings
are central to the phenomena they study – and so do Skinnerian
radical behaviorists. Mainstream psychologists also formulate
theories purporting to explain phenomena that cannot be
observed directly – and radical behaviorists, too, have done so
for a long time (e.g., Skinner, 1969). Still, an important difference
is the radical behaviorist belief that “initiating” causes exist only
in the environment. Mainstream psychologists do not share this
assumption. Might it be possible, then, that if behaviorists were
to accept a line of argument like that advanced in the present
article, a reintegration into psychology proper could take place?
The present author would be tempted to say yes.
The present author might be wrong, however. For instance,
there are certain practices and certain areas of research that are
quite specific to behavior analysis, even if they do not necessarily
depend on theoretical assumptions that are specific to that field.
Incentives may exist that preserve such traditions, even if they
may not be the most effective way of acquiring knowledge (see
Vyse, 2013). This may indicate that a change in theoretical
outlook, if it were to happen, would not necessarily lead to a
change in practice.
Moreover, it is sometimes said that new ideas are not accepted
on account of facts and arguments, but because those who hold
the old ideas die out. If there is truth in this, it may be due to
social mechanisms such as the shared world view that is typical of
many groups (see Peñaloza and Venkatesh, 2006), and cognitive
mechanisms like confirmation bias (e.g., Doll et al., 2011) – things
that aren’t easily changed. Yet facts are stubborn things – more
stubborn, it seems, than human minds. That’s why paradigms do
change, after all, and also why debate in science is worthwhile.
The author confirmed being the sole contributor of this work and
approved it for publication.
Bach, P. …