Uri Geller: Self-Proclaimed ‘Psychic’

A flash-back to 1975 when Uri Geller came to town.  Super-psychic or super-charlatan? Who to Believe?

On the one hand, a scientific report published in Nature verifying Geller’s psychic abilities under supposedly cheat-proof conditions, and on the other, a highly speculative but critical attack published simultaneously in New Scientist. While Targ and Puthoff’s reply … would seem to invalidate his explanations of their significant results, it is difficult to disregard the doubts Hanlon has raised about the “circus atmosphere” that he believes surrounded the SRI experiments. Frankly, at the end of 1974, we were puzzled and confused. Weighing all the evidence available at that time, it seemed impossible to decide whether Geller was a genuine psychic or an ingenious and highly skilled hoaxer. Clearly, the Geller effect had to be taken seriously as, in either case, there would be much of interest to learn about the mechanics of psychic performance. Clearly, what was needed was more experimentation.

First Encounter

Our first live encounter with Geller was accidental. On 23 March 1975 Geller arrived in New Zealand from Australia to begin a series of four “lecture-demonstrations” of his psychic powers. To facilitate communications, I ( David Marks) checked into the same hotel as Geller in the Dominion capital, Wellington. Hopefully we could obtain a sufficient level of cooperation to complete a series of laboratory tests. I left a letter for Geller at the hotel reception inviting his participation in some experiments.

I had been told by Geller’s local agent, Bruce Warwick, that Geller was due to arrive on the ten o’clock plane, and so an arrangement was made to talk with Geller the next morning after a press conference. At eight o’clock on the evening of the 23, I went down to dinner in the almost empty hotel restaurant. At about nine o’clock a party of noisy, flamboyant people sat down at the table next to me in the quiet dining room. From their accents, some were obviously Americans, others Australians, and others sounded like Americanized Israelis.

Suddenly, as I idly scanned their faces, to my utter amazement, I saw Uri Geller. Apparently, he had materialized himself into New Zealand prior to the aircraft’s arrival! He was sitting with his back to me, not more than ten feet away, opposite a woman with blond hair who spoke loudly and clearly with a distinct American accent.

Geller’s Faux Pas

Although I was dying to meet Geller, my first reaction was to leave, as the last thing I wanted to do was invade Geller’s privacy. However, it was I who had been there first, and they had sat next to me, not vice versa, so I decided to finish my dinner and then leave.

To this day I can still hardly believe what took place in the next few moments. The American woman (whom I knew later to be Miss Solveig Clark, one of Geller’s personal assistants) asked Geller in a clear and distinctive voice whether he had “read the letter from Dr. Marks.” Like most other people, I find it hard not to tune in to a conversation when my name is mentioned. I heard Geller reply: “Keep that guy away from me; he’ll pick up the signals (sic).”

No words can describe how I felt at that moment. What signals? Could these be the signals described in the New Scientist? Who was Geller’s female confidante? Was Puharich there, or Shipi Shtrang? Although I couldn’t answer all these questions, Geller had already told me more than I ever imagined would be possible. Yet Geller was blissfully ignorant of this major faux pas. I couldn’t help feeling that if Geller were truly psychic, he’d certainly have sensed my presence and avoided giving away trade secrets!


No question about it, from that moment I sensed that Uri Geller was nothing more than a not-so-clever trickster.

Anybody can bend a spoon, as long as you have a firm grip. Try it without touching, however, and its a very different story.

Geller successfully conned pretty much the whole world into believing he had special powers.

He does. It’s called sleight-of-hand!

Flashback: an extract from “The Psychology of the Psychic”.

A New Ponzo Illusion

Most visual illusions are produced using carefully contrived drawings or gadgets to fool the visual system into thinking impossible things.  Recently,  waiting at a train station, I encountered a real-life Ponzo illusion.

The Illusion

The traditional form of the Ponzo illusion is produced by drawing a pair of receding railway lines. The context suggests different depths in the drawing. An object towards the top of the drawing appears larger than an identical object near the bottom of the drawing.  Using a principle of size constancy, the visual system estimates the size of any object as its retinal size multiplied by the assumed distance. Thus, the ‘most distant’ of the two identical yellow lines appears to be longer.


The Setting

The setting of this new Ponzo illusion is a railway station situated at Vitrolles Airport, Marseille (see photo below).  The station has glass panelled shelters on the platforms on each side. The glass panel at the front of each shelter displays two rows of grey rectangles. Apart from their decorative function, one assumes that these rows of rectangles are intended to help prevent people from walking into the glass panel as they move in and around the shelter. The photo below shows the arrangement of the two rows of rectangles on the shelter.


The Stimuli

The stimuli for the illusion consist of rectangles that are slightly longer than a credit card, approximately 10.0 cm long x 1.5 cm wide with a separation of about 3.0 cm between successive rectangles. The plate glass window is about 5 mm thick and is marked with rectangles on both sides of the glass in perfect alignment so that a 3-D effect is created indicating a false sense of solidity to these rectangles. This ‘3-D look’ may strengthen the Ponzo effect illustrated below.


The Illusion

The illusion is demonstrated in the photo below.  Two people sitting directly in front of the shelter are waiting for a train. The upper set of rectangles appears as a set of columns positioned along the railway lines at a distance of approximately 7 metres in front of the two passengers. In this case, the upper set of rectangles appear to have a height of around 2-3 metres. The lower set of rectangles are perceived at their correct location and size on the plate glass window, behind the two passengers. The lower set are actually physically smaller, owing to the camera angle, but the illusion exaggerates the size difference enormously.


Further illustration of the effect indicates how the brain scales the stimuli to the context. When the rectangles are projected onto the opposite platform they appear huge – almost as high as the lamp post of around 5 metres.

When the rectangles are projected onto the nearby platform, however, they appear proportionately smaller (1.0-1.5 metres).


IMG-9389.JPGOwing to the camera angles, the actual size of the rectangles in the upper picture is larger (5-10%) than in the lower picture, but nowhere near the illusory ‘expansion’ that takes place when they are projected by the brain to the opposite platform.

Blocking the Distance Cues

The magnitude of the Ponzo illusion becomes somewhat indeterminate when the distances cues were fortuitously blocked by a passing freight train. In this case the rectangles are ‘drawn into’ the scale of the passing wagons, stretching in size beyond the appearance when the wagons are not there.



The Ponzo illusion can be most easily explained in terms of linear perspective. The rectangles looks longer when they are projected to the distance of the opposite platform because the brain automatically interprets them as being further away, so we see them as longer. An object located farther away would have to be larger than a nearby object to produce a retinal image of the same size.


The more visual cues surrounding the two vertical lines, the more powerful the illusion. The passing freight train obliterated some of the distance cues and so the length of the lines were more difficult to assess.

The Strange Self-Motion Illusion

Anomalous experiences tend to jolt one out of one’s comfort zone, tell us interesting things about how the mind works.  A vivid déjà vu, strange coincidence, or unexpected illusion can all be automatic attention-grabbers.  Some of the oddest experiences are visual. When a large part of the visual field moves, the viewer can momentarily believe that they have moved in the opposite direction.

The most common example occurs when looking out of a stationary train window at a station, and a nearby train moves away, you erroneously perceive that your own (stationary) train is moving in the opposite direction. This experience can happen on the railway, the road, at sea or in space, and it can cause accidents (e.g. see https://safety4sea.com/relative-motion-illusion-leads-to-collision/).

The other day, driving along a busy A3 towards London on ‘autopilot’ (Vatansever, Menon and Stamatakis, 2017), I reached a  set of traffic light. In the middle lane, my vehicle was boxed in all sides by other vehicles so that I could not myself see the traffic lights. Suddenly I felt as if my vehicle was being pulled backwards so that my car would impact the one behind, a potential disaster.  I immediately slammed my foot on the brake and felt a surge of adrenaline. Thankfully, my perceptual-motor system quickly snapped back to reality – I realized that I was stationary and that the surrounding vehicles were moving forwards.  Reset! In less than a second, my foot came off the brake and onto the accelerator.  I had experienced the ‘Self Motion Illusion’ (Riecke, 2010).

My brain had falsely concluded that my vehicle was moving backwards. This is the natural response of a perceptual system with a default setting that expects constancy (Day, 1972).  I wish to argue that perceptual constancy is based on a universal principle of ‘Psychological Homeostasis’ (Marks, 2018).  When my perceptual world went haywire at the traffic lights, a rapid correctional ‘reset’ brought me back to my senses.

The rapidity of the reset is required to prevent a potential accident. This fact may be evidence of a general reset principle which is operating to produce equilibrium at each and moment in a conscious being.  Alternatively the experience was reset by the fact that I saw the surrounding vehicles moving away around me. It is hard to say from a single uncontrolled experience.


Day, R. H. (1972). The basis of perceptual constancy and perceptual illusion. Investigative Ophthalmology & Visual Science11(6), 525-532.

Marks, D. F. (2018). A General Theory of Behaviour. London: SAGE Publications.

Riecke, B. E. (2010). Compelling self-motion through virtual environments without actual self-motion–Using self-motion illusions (‘vection’) to improve VR user experience. Virtual reality. InTech.

Vatansever, D., Menon, D. K., & Stamatakis, E. A. (2017). Default mode contributions to automated information processing. Proceedings of the National Academy of Sciences114(48), 12821-12826.