The Excitable Membrane

Yeah, I know. I’ll confess I find it pretty hard to get pumped about studying reaction times. It seems James is a kindred spirit here, noting that the literature on it is the “sort of work which appeals particularly to patient and exact minds.”

But since reaction time is one of the few toeholds he has on what he calls “psycho-physical” processes, he goes big, and comes up with some surprisingly deep principles that he’ll cash out later in later chapters on memory, attention, and other psychological phenomena.

As we’ve seen before, James is an expert summarizer and synthesizer of scientific findings, and he’s in top form here. We’re not interested in calculating reaction times just to have an exact answer to the question “how much time elapsed between when the starting gun went off and the runners started moving?” What we’re really after is an estimate of the quickness of a concrete intervening thought like “I should start running!” or “Ooh! That was the gun!” A reaction time doesn’t measure things like this directly, and arguably it doesn’t even do it indirectly, but experiments like this have the virtue of setting up a measurable mental (of sorts) act that has a highly contingent and controlled relationship with the environment. James calls this kind of situation one of “simple reaction-time, in which there is one possible signal and one possible movement, and both are known in advance.” I hadn’t thought about reaction times much before reading this chapter, but I’ve come to appreciate what an interesting state of tension and control it is to be waiting for a starting gun. The internal experience is one of having handed control over the environment, yoking ourselves to it in a kind of weird anti-flow state. James describes it as “a state of extreme tension,” and one has the sensation, “when the signal comes, as if it started the reaction, by a sort of fatality, as if no psychic process of perception or volition had a chance to intervene.”

A best case scenario for a psychologist trying to clock the mind is that the “I should run!” thought occurs fully within a time interval bookended by the sound of the starting gun and the first muscle contractions, meaning we can use this interval as an upper bound for the speed of thought (at least under these super constrained circumstances). If we have estimates of a how long it takes signals to traverse sensory and motor nerves, we can ballpark how long the intervening transformation from sensory (gun) to motor (run) takes by subtraction. This is all well and good, but James is skeptical about what we really learn about minds from this kind of analysis. His colleague Wundt is all about reading the tea leaves of mentation from reaction times, and although James agrees with him that some feeling likely unfolds during the reaction interval, it’s hard to pin down exactly what this is. This is because the feeling “is so fugitive and immediately eclipsed by the more substantive and enduring memory of the impression as it came in, and of the executed movement of response.” In other words, we have to be on the lookout for retrospective, storytelling tricks of memory that try to backfill what happened during earlier times. The gun went off, and then I ran, so I must have had the thought “Run!”, right? Brains like to tell stories that gratify the ego, and which make us seem like a godlike locus of control rather than a subservient minion. On balance, James says, what we measure in a reaction time experiment is, “in short, a reflex action pure and simple, and not a psychic act.”

Even his buddy Wundt seems to have come around eventually, acknowledging that “there is neither apperception nor will” during reactions, and that “they are merely brain-reflexes due to practice.” The decisive experiments that led Wundt to change his mind were ones by Lange, who made a distinction between “extreme sensorial” and “extreme muscular” ways of performing a starting gun style task.

Consider the two different sets of instructions: 1) listen intently for the starting gun, and once you hear it, then start going (extreme sensorial); 2) move as soon as you hear the gun (extreme muscular). Operationally, the task is the same in both cases in that a gun will go off and then a stationary person will move some measurable time later. In practice, though, reactions for the second set of instructions tend to be about twice as fast. Summarizing this, James underscores his earlier point. “These reaction time experiments are then in no way measurements of the swiftness of thought. Only when we complicate them [i.e. by making them of the ‘extreme sensorial’ type] is there a chance for anything like an intellectual operation to occur.”

I find it really cool that we have this mental gear that we can throw into place that makes our behavior almost fully conditional on the environment. It’s like the opposite of meditation, where the goal is to have thought be captured by and conditional on nothing.