What is remembering, and why don’t we remember when we were toddlers?

I started this post because I wanted to address the second question, but it quickly became apparent that my answer required first dealing with a more fundamental set of questions about memory and remembering.  As background, take a look at Box 5.3 in Radical behaviorism for ABA practitioners, but we’re going to go deeper than that here, so make sure you’re pretty solid with Chapter 2.

The place to begin is by dispensing with the notion that there is such a thing as memory.  Although there are some real, physical phenomena to explain, it is important to be careful what we call them and what attributes we assign.  The phenomena are what they are, but the terms we use to describe and explain them are, as the title of Chapter 2 suggests, “just verbal behavior.”  This characterization should preempt the traditional vocabulary of this topic in favor of a more illuminating conceptual approach proposed by B. F. Skinner in his famous paper, The operational analysis of psychological terms (Skinner, 1945). (See Box 10.4.)

In this application of Skinner’s argument, the challenge is not just to avoid rampant mentalism in both scientific and vernacular discussions of of memory and remembering.  Although this is an important objective, successfully evading the temptations of mentalism does not resolve the more difficult problem of being clear about the sources of control over our verbal behavior.  Even when we are talking about remembering as behavior, much remains to be specified.  For example, when someone misplaces a set of keys and then recalls where he or she last saw them, is it the same phenomena as when a rat responds in an experimental preparation on the basis of exposure to a prior stimulus that is no longer present?  The question is not whether we might be tempted to say that both organisms “remembered” – surely too casual a label – but whether any distinguishing features of the two circumstances might be the basis for proposing that they may be somewhat different phenomena.

The reason for distinguishing among the different physical phenomena involved and giving them different labels is to encourage scientifically useful distinctions.  This is a considerable task because it requires us to know enough to make these discriminations, which is the centerpiece of the research agenda in the first place.  For example, scientists who study what is going on in the brain when people engage in the behavior of remembering – and let’s remain clear about this distinction between biology and behavior – refer to various measured physiological events as “storing” or “recalling” memories.  Even more grandly, these physiological events may be described as “memories” or even as “remembering.”   Different studies using different procedures and measuring different physiological events imply that the same phenomena are being studied when the label “memory” and related terms are broadly used in publications.  Although the scientific dialect in memory research is in one sense precise, thanks to the sophistication of our ability to directly measure physiological processes, it is also sloppy because the conceptual zeitgeist in this area allows unfounded assumptions, not to mention unrepentant mentalism.

Let us count (some of) the ways

Consider different ways we talk about the behavior we call remembering, keeping in mind the challenge of evaluating the sources of control over such verbal behavior.  In everyday parlance, we often say we are remembering when we can describe something in our past to ourselves or to others.   We are likely to say we are remembering when we “see” a visual image of something from our past that is not now present, whether the image is simple and brief or more complex and extended in time.  (Chapter 4 explains seeing in the absence of the thing seen.)  However, it is possible that when we do this we are sometimes only tacting our verbal behavior of previously “reporting” the memory.  That is, when we say, “I remember the time…” what are we actually doing?  Are we engaging in sensory behavior as if we were again in some past situation, such as seeing or hearing in the absence of the event?  Or are we just saying something we have said before about an early “memory” but not actually again experiencing the events themselves in any way?  If so, these would seem to be different behaviors that should have different labels.  (I will not get into the topic of false memories.)

Another circumstance in which we say we are remembering is when we do something that we have done before, presumably enabled by our prior experience.  I might say, “Do you remember how to get to Chris’s house?  And you might say, “Sure, I’ve been there lots of times.”  If you successfully get there, does that mean you actually remembered or were explicitly aware of features of the route?  This way of labeling remembering is troubling because it can be no more than a convenient label for the results of experience.  Taken to the extreme – and this may be what we’re doing – it only assures that such references are redundant with the processes of operant learning.  If we say that anything we do that we have done before involves remembering, the term becomes worth not much at all – a casual vernacular throwaway – because it is not distinguishable from operant learning in general.  When you reach for your coffee cup and take a sip, are you remembering how to do this?  Is this the same phenomena as remembering your first pet?  More on this point later.

We seem most likely to refer to the act of remembering only when we are tacting our own behavior, although this is still an expansive usage.  If you privately “sense” a prior event or situation, you are aware or conscious of it.  As Chapter 4 points out, this means you are tacting the event or situation in some way.  If out of the clear blue you see the first car you owned or hear a tune you like, that act of sensing is behavior.  Such sensing behavior is certainly associated with physiological events in your brain, but it is not the same thing.  Putting aside whether we should call the visual or auditory image a memory, the fact that you are aware of such sensations is behavior.  By being aware you are responding to it verbally, however loosely.  You can’t be responding to the actual event, which is not present, but whatever is going on in your brain is the physiological basis for emitting the response of seeing your first car or hearing a tune.  This response of recognizing or labeling the sensation is at least a minimal form of verbal behavior.  Such simple verbal responses are the essence of what we mean when we say we are aware or conscious.

This qualification – having a self-descriptive repertoire or being able to tact our own behavior – would seem to preclude the possibility that non-verbal organisms can engage in this behavior, whatever we want to call it.  More cautiously, the fact that this learned self-descriptive ability seems to influence whether we label behavior as remembering suggests that it might be useful to distinguish this kind of responding from otherwise similar responding for which awareness is not apparently possible.  So, the behavior of a rat that responds in a certain way in an experimental chamber based on experience with stimuli that are not now present might best be labeled differently than the behavior of a verbal human under similar circumstances.  We cannot know if this is a useful tactical distinction until research eventually tells us one way or the other.  I will come back to this point as well.

Perhaps we at least ought to distinguish between physiological events and behavioral events that the term “remembering” seems to be associated with, even though each depends on the other in fundamental ways.  When we engage in any behavior, there are unavoidably corresponding physiological events that must be part of any comprehensive explanation of it, and some of these events involve the brain.  Although this subdivision between behavior and biology is useful in guiding research, it is artificial.  Nevertheless, it is important to appreciate that what goes on in the brain cannot fully drive or explain what happens with behavior.  The reason for this limitation is that although learning processes are ultimately mediated physiologically, they involve the intact organism’s interaction with the environment.  We may some day be able to explain exactly what is happening in the brain when a particular behavior occurs, but that explanation will not reveal why the behavior occurred in that way at that moment.  That part of the explanation requires understanding the behavioral aspects of learning.  Although they are fundamentally intertwined with physiological processes, they involve different levels of explanation.

Don’t lose sight of the purpose of this conceptual exercise.  We are considering our verbal behavior of saying that we – or others – are engaging in a particular kind of behavior.  The challenge is no different than labeling the behavior of a child as “tantrumming.”  It is a response class problem: what responses and associated stimulus relations belong in the class and what don’t.  If we wish to label a response class as remembering, what responses should be included and excluded?  The underlying problem is that neither scientists nor ordinary folk know enough about the features and limits of the phenomenon of remembering at either the level of behavior or physiology to be sure of our answers.  We can at least respect the tactic of analyzing the sources of control over our labeling behavior.

But enough with scientific and conceptual tactics.  For purposes of discussion, let’s agree for now to define remembering in terms of what is arguably its most common colloquial reference – tacting a private event in our past that we are sensing in some way.  That is, let’s say that when we remember, we are engaging in the behavior of sensing (seeing or hearing, most commonly) an event that we have previously experienced but that is not now occurring.  The fact that these responses take the form of sensing particular, recognizable events may be described as tacting.  The event might be something simple and brief, such as a visual image of our first tricycle, or complex and extended in time, such as various experiences (usually visual) associated with a vacation trip.  We do not have a visual image of a tricycle and then tact it as such.  Seeing the tricycle is itself the response of tacting, albeit private.  This definition of remembering is certainly not all there is to the phenomena, but it is at least how we are often taught by our verbal community to label this kind of behavior.

Now, the first question

With all this preparation, we should now be in a better position to address the second question:  Why do we not seem to remember anything from when we were a baby or even a toddler, say from birth to the age at which first memories are typically reported – about three years of age?  The answer is hidden in the above discussion.

First, it is probably important to acknowledge that it may take a bit of time for us to accumulate sufficient experience for the brain to develop the structure and neural connections that are at the physiological root of the behavior of remembering.  This limitation may be a sufficient explanation for not remembering anything from the earliest few months of life.  However, it is presumably not a viable basis for not remembering events later in the first year and beyond.

Second, in explaining the behavior of remembering as I am defining it in this discussion, we must acknowledge that it is entirely learned from our verbal community.  That is, we cannot assume that the behavior of sensing – tacting – events we have previously experienced but that are not now occurring magically appears merely as a result of being human.  Given our working definition, remembering clearly requires a verbal repertoire, and Chapter 2 briefly explains how this repertoire can only results from learning processes mediated by members of a verbal community.  In fact, we know a lot about how this verbal skill develops, especially in the early years.  Like other complex features of our repertoire, our verbal capabilities build fairly slowly.  Chapter 2 notes that there isn’t much more than babbling during the first six months, and the first words at around 11 months don’t exactly make much of a verbal repertoire.  Even by three years, a vocabulary of 800 words is a pretty small sample of where things will eventually go.

It’s not just a matter of the size of the vocabulary, however.  These 800 words or so are part of a rudimentary skill of tacting the world around us, including our own behavior.  It is this capability that is required for the behavior of remembering.  As we learn to tact our behavior, our ability to remember grows.  At first, the challenge is just to report things that we did recently, such as what we had for breakfast or where we put a toy.  As we get better at noticing and describing our present behavior, we improve our ability to describe our past behavior.

In other words, if we did not learn to tact our behavior and our interface with the world around us, we would have no means of remembering, as defined for purposes of this discussion.  Because what we colloquially call remembering most often involves recognizing or describing events in our past, such behavior is not possible until we learn to do this.  We don’t remember our experiences very well prior to getting pretty good at the verbal behavior of remembering.  Of course, this ability develops gradually and at a different pace from one child to another, so the age at which we can later report our earliest memories varies somewhat.

This argument should not be surprising.  Chapter 4 discusses the radical behavioristic view of awareness in this same way.  Awareness is fundamentally about our ability to observe our own behavior, and these observations involve recognizing – in effect, tacting or describing – what we are doing.  We are accustomed to not being able to recall experiences that we had but were not aware of at the time, such as driving while lost in thought.   We initially encounter our early childhood experiences without awareness, and develop the skills of self-observation and self-description only slowly.  At some point, our self-observation gets sufficiently practiced that we are aware of more of our experiences and are able to tact them when they occur and sometimes long after the fact as well.

However…

The rebuttal to this argument is that we are accumulating memories prior to learning a self-descriptive repertoire but have no means of expressing them – a position that may be difficult to falsify.  In any event, there is no question that we engage in remembering behavior of some sort prior to the age of three.  Parents can point to many instances in which their toddlers describe prior experiences, but such reports are about relatively recent events and limited in detail compared to what we can recall in later years.  Most of these early instances of remembering are probably what memory researchers call short term, rather than long term – a distinction for which there may be more physiological than behavioral justification thus far.  Another way of putting it is that our self-descriptive ability is acquired only gradually, and we might expect that in the early stages its effects would be weak.

I suspect some would also like to argue that non-human species engage in some form of remembering behavior but, being non-verbal, are similarly constrained.  In both laboratory preparations and more casually at home, it’s undeniably easy to observe behavior in other species that we have been taught by our verbal community to call remembering.  We see a pigeon responding correctly on the basis of exposure to prior stimuli that are no longer present or our faithful dog doing the same thing when we ask it to go get its leash.  We say that they remembered certain prior events, implying that this characterization is a key part of the behavior’s explanation.

These observations suggest two questions, however: How can we distinguish such behavior from the effects of mere operant history, and should we distinguish such behavior from the kind of remembering exhibited by verbal humans?  The first question is the more difficult of the two.  We understand operant learning processes quite well at this point, and it is clear that our behavior is substantially influenced by past contingencies.  This history leaves a rich trove of opportunities to identify past experiences and to propose that their unavoidable influence is mediated by a distinctive process called remembering.  But what is the evidence for remembering as a process that is distinct from and supplements operant learning?  Are we merely being too casual in throwing around the term “remembering?”  What have we added to the explanation with this term?  Are we simply making up a “phenomenon” free of physical dimensions on the basis of our vernacular dialect?  If so, isn’t that what we call mentalism?  Even if research showed direct evidence of physiological events going on in the brain under controlled test conditions that might justify this label, such events would need to be different from those ordinarily reflecting operant behavior in order to usefully serve as the basis for proposing a “remembering” phenomenon that is distinct from what we already know about operant learning.  Lacking such evidence, reference to remembering as an omnipresent feature of operant behavior merely because of the unavoidable role of past events seems gratuitous.

The second question takes us back to where we started.  How do we manage our scientific vocabulary?  Guided by Skinner’s standards, our ideal is to ensure that the sources of control over our verbal behavior lie primarily in sound experimental evidence, not in our social history.  More realistically, we try to constrain our talk about behavior with the findings of our science and their implications, as well as with strategic objectives such as avoiding mentalism.  This research tells us that when we are young we learn a distinctive skill formally called tacting.  The development of this skill gradually extends to our own behavior and its environmental context, which we refer to as a self-descriptive repertoire and as a prerequisite for the phenomenon of awareness.  Because non-verbal organisms generally have no means of learning this skill (lacking the benefits of a verbal community), it is reasonable to guess that they cannot do what we verbal humans do when we remember.  As I noted earlier, this suggests that at least for now we should distinguish between verbal and non-verbal repertoires in referencing whatever we might wish to call remembering.  In other words, whatever is at the root of what we might like to call the behavior of remembering, it would seem that verbal humans do it somewhat differently than non-verbal organisms.  It might be wise for us to reflect these differences in our technical vocabulary.

This all started with the general issue of why our memories of our childhood seem to begin only after we are a few years old.  The answer is that remembering in the most frequent sense of the word requires a self-descriptive repertoire, which is inherently verbal.  Until that repertoire develops to a certain point, we are not especially aware of our behavior and its environmental context because the contingencies established by our verbal community have not yet led to an adequate way of describing it or the events in which we participate.  In other words, we do not remember under these circumstances because we have not learned how, just as we do not remember events throughout our lives when we are unaware of them.