Psychology and stage magic

Psychology and stage magic

Exploring the role of demand characteristics

This post was published in Psychology Review 29(1)

Photo by Julius Drost

Picture the scene. Four people on stage, shuffling sideways in a circle. They are facing inwards, each with both palms face down on the top of a round coffee table. The table is rotating of its own accord. Their job is simply to follow it where it goes. We’re told it’s a kind of séance.

The instructions had been perfectly clear. When the table started to move (powered, of course, by energy from beyond the grave) they were to move with it. They were not to exert any force themselves. The table had begun its journey by heading to the front of the stage. It had then come back to the centre of the stage (conveniently, some might say) before starting to spin.

Its speed of rotation quickens. The audience is informed that this is the table ‘finding the room.’ While it is turning, each person is asked in turn if they are ‘pushing it at all?’ They all reply, ‘No’.

Intriguing. Quite how the table is moving is a complete mystery…

The swinging pendulum

Immediately before the table thing, there had been a pendulum thing. About ten audience members had been invited onto the stage. They were each given a weight on a string and lined up in a row. Their task was to hold the pendulum at arms-length, stand perfectly still, and use their mind to will the weight to swing.

After a few seconds one or two of the weights started moving. Before long, several weights were swinging backwards and forwards. The participants who had been most successful in using their psychic powers to cause their pendulum to swing were asked to step forward.

Misdirection

Now, let’s get one thing straight. I don’t pretend to know how Derren Brown does his thing. He is a spectacular performer and I thoroughly enjoyed watching one of his live performances, as well as a recorded version of the sequence described above (Moving a table with psychic energy?). So, please understand that the analysis I am going to give is my best guess, based on a good knowledge of psychology, and a very limited understanding of the craft of the stage magician.

One thing I do know about stage magic is that misdirection is a key element. The performer gets the audience to focus on one thing, while doing some kind of manipulation of another thing. It’s my view that one of Derren Brown’s characteristic misdirections is to get the audience to ‘look’ in the wrong direction by making them think he is doing something ‘psychological’, while all the time he is doing standard stage magic. I’m using ‘standard’ in a non-pejorative sense, to mean something that other magicians would recognise as part of a repertoire of techniques. In terms of entertainment, it’s anything but standard. It’s terrific!

That assertion notwithstanding, it’s also clear that he does use psychological principles in some of his magic. His riff on the gorilla ‘inattentional blindness’ paradigm can be seen here: Gorilla observation test. In the original experiment (Simons and Chabris, 1999), a person in a gorilla suit walks through a group of basketball players but viewers fail to see the gorilla. In Brown’s version a gorilla allegedly enters the stage at some point during the performance, unnoticed by most of the audience. I say allegedly, because, despite knowing about the original experiment, I didn’t see it! Or rather I only saw it when it made an obvious reappearance on stage, and, in a neat twist, it turned out to be Derren Brown himself in the suit.

Demand characteristics

The revolving table trick represents another of his uses of psychological principles. It seemed clear to me, when watching this, that the preceding swinging pendulum sequence was but a selection mechanism. He wanted to see which participants would make the weight move the most (through slight movements of their arm and shoulder, of course). This would indicate which of them were the most motivated to make Brown’s stage magic work. These were the ones he picked for the séance malarkey.

I’m hoping that you will have no trouble in identifying this as an example of ‘demand characteristics’ in action. In experimental psychology the demand characteristics of a task are those cues that signal to the participants how the experimenter ‘wants’ them to behave. They are the cues that let the participant know what is being ‘demanded’ of them. Note, the experimenter may or may not have intended these cues to be present.

Human participants, who cannot stop themselves trying to make sense of things, will always be on the look-out for ways to interpret what is going on. They will also, as a rule, be compliant and helpful. After all, psychology experiments are a force for good, aren’t they? If we are asked to take part in an experiment, we might reasonably assume that it is a well-motivated piece of work and aims to add to the useful stock of human knowledge.

A self-fulfilling prophecy

The problem for psychological researchers is that, having made sense of what it is that is being demanded (expected) of them, the helpful participants will have a tendency to behave in line with that sense-making. In other words, they may behave in ways that have been influenced by what they believe the experimenter’s expectations to be. Since the experimenter’s expectations are, in fact, summarised by the experimental hypothesis (which is literally a statement of the expected patterns of behaviour, averaged across participants), we have all the ingredients for a self-fulfilling prophecy in play. A self-fulfilling prophecy is defined as a prediction that comes true, at least partly as a result of a person's expectation that it will come true.

This is where experimental psychologists sometimes do their own misdirection. They make efforts to deceive their participants into thinking an experiment is about one thing, when it is in fact about another. That way, they are able to contest any accusation that their findings are best explained in terms of the demand characteristics of the experiment. See the obedience study by Milgram (1963) for a famous example of this.

Positive feedback

Back to the séance. The four audience members selected to stand around the table were evidently highly motivated to take part in a successful performance. They had read the available cues to make sense of what was being demanded of them. They were compliant and wanted to make the trick ‘work’. And although they were probably each authentic in their belief that they were not intentionally exerting force onto the table to make it move around the stage and rotate, it is clear that they must have been doing exactly that.

This brings us to another way in which psychological principles were being deployed. One might hypothesise that the slightest movement of the table in one direction, perhaps caused subconsciously by one of the participants (or is one of them a confederate?), would be perceived by the other participants as ‘the table starting to move.’ In ‘following’ that movement with the palms of their hands, it’s likely that some further force is exerted. This further exaggerates the movement. Each participant interprets this movement as coming from somewhere else (not them!) and encourages still more force to be exerted as they each work at keeping their palms in contact with the table.

This is an example of positive feedback in a feedback loop. Don’t confuse this with the behaviourists’ concept of positive reinforcement or with getting nice comments on your work. In this context ‘positive feedback’ (also known as ‘exacerbating’ or ‘error-amplifying’ feedback) refers to a sequence of events that feed off each other to intensify some aspect of a process. This concept is used in areas of interpersonal psychology (family systems psychology and cybernetics) to understand interactions such as arguments. One person raises their voice. The other person raises their voice a little more when they reply. The first person responds in kind. Each reaction causes the next response to become further amplified. Before long, a blazing row is in full swing.

Applying psychology

Psychology can be a dry old subject, sometimes. Reading about demand characteristics, deception as a feature of experimental design, and feedback loops can be wearisome. So, it’s interesting, on occasion, to take a look at what these things might also look like ‘in the wild’ (as it were) away from the usual psychology textbook topics.

Needless to say, I might be wrong about precisely how these ideas were being used in the show in question. But in many ways, it doesn’t really matter if I am. Our understanding of concepts from psychology is invariably enhanced when we make the effort to apply them, rationally, to questions that are of personal interest to us. And my hope is that your understanding of these ideas has been enhanced by considering them in the intriguing context of superbly performed stage magic.

Derren Brown’s comments

We sent this article to Derren, who wrote:

“Andy has nailed it! ‘Ideomotor suggestion’ is behind the mysterious movement of seance tables and ouija board planchettes, and can be just as eerie and unfathomable as it was a hundred and fifty years ago. And yes, the table would often ‘conveniently’ settle back centre-stage as that’s what felt right to the people who were unconsciously pushing it. Find a smallish table - no need for wheels - a shiny wooden floor and three or four volunteers and give it a try. As long as you can get them to expect movement, and instruct them to ‘follow’ it whenever it starts to move, you should find you can get this going. It’s a wonderful thing to see.“

 

References

Milgram, S. (1963) 'Behavioral study of obedience', Journal of Abnormal and Social Psychology, Vol. 67, pp. 371–378.

Simons, D. J. and Chabris, C. F. (1999) ‘Gorillas in our midst: sustained inattentional blindness for dynamic events’, Perception, Vol. 28, No. 9, pp. 1059-1074.