Shufflebrain

The loss of detail that occurs when we decode a small piece of diffuse hologram is not a property of the code itself. Blurring is a result mainly of noise, not the signal. How seriously noise affects the quality of an incoming message depends on the ratio of noise to signal. If the signal is powerful, we may dampen noise by reducing volume or brightness. But with very weak signals, as short-wave radio buffs can testify, a small amount of noise (static) severely impedes reception. In optical holograms, the relative level of noise increases as the size of the hologram decreases. And in a small enough piece of hologram, noise can disperse the image.

We have already made the analogy between the survival of memory in a damaged brain and the survival of image in a marred hologram. Signal-to-noise ratio is really an analog of the decline in efficiency found in Lashley's subjects. In other words, the less brain, the weaker the signal and the greater the deleterious consequence of "neural noise."

***

Loss of detail in an image produced from a small chip of hologram is a function of decoding, not of the code itself. An infinitesimally small code still exists at every point in the diffuse hologram. Like a single geometric point, the individual code is a theoretical, not a physical, entity. As with geometric points, we deal with codes physically in groups, not as individuals. But the presence of a code at every location is what accounts for the demonstrable fact that any arbitrarily chosen sector of the hologram produces the same scene as any other sector. Granted, this property may not be easy to fathom; for nothing in our everyday experience is like a diffuse hologram. Otherwise, the mind would have been the subject of scientific inquiry long before Leith and Upatnieks.

***

If a single holographic code is so very, very tiny, any physical area should be able to contain many codes-- infinitely many, in theory.^[1] Nor would the codes all have to resemble each other. Leith and Upatnieks recognized these properties early in their work. Then, turning theory into practice, they went on to invent the "multiple hologram"-- several totally different holograms actually stacked together within the same film.

With several holograms in the same film, how could reconstruction proceed without producing utter chaos? How might individual scenes be reconstructed, one at a time? Leith and Upatnieks extended the basic operating rules of holography they themselves had developed. During reconstruction, the beam must pass through the film at a critical angle-- an angle approximating the one at which the construction beam originally met the film. During multiple constructions, Leith and Upatnieks set up each hologram at a different angle. Then, during reconstruction, a tilt of the film in the beam was sufficient for one scene instantly to be forgotten and the other remembered.

One of Leith and Upatnieks' most famous multiple holograms is of a little toy chick on wheels. The toy dips over to peck the surface when it's dragged along. Leith and Upatnieks holographed the toy in various positions, tilting the film at each step. Then, during reconstruction, by rotating the film at the correct tempo, they produced images of the little chick, in motion, pecking away at the surface as though going after cracked corn. Some variant of their basic idea could become the cinema and TV or tomorrow.

***

Multiple holograms let us conceptualize something neither Lashley nor anyone else had ever satisfactorily explained: how one brain can house more than one memory. If the engram is reduplicated and also equally represented throughout the brain, how can enough room remain for the next thing the animal learns--and the next...and the next? Multiple holograms illustrate the fact that many codes can be packed together in the same space.

Just as important, multiple holograms mimic the actual recalling and forgetting processes: tilt the film in the reconstruction beam, and, instantly, off goes one scene and on comes the next. A few years ago, I met a young man named John Kilpatrick who suggested that a person trying to recollect something may be searching for the equivalent of the correct reconstruction angle.

But suppose that instead of using a single reconstruction beam, we use several beams. And suppose we pass the beams through the multiple hologram at different angles. We may, in this manner, synthesize a composite scene. And the objects in the composite scene may never have been together in objective reality. When the human mind synthesizes memories into unprecedented subjective scenes, we apply terms such as thinking, reasoning, imagining; or (depending on the circumstances) even hallucinating. In other words, built right into the hologramic model are analogs of much human mental activity.

***