The cocktail party effect describes the ability to focus one’s listening attention on a single talker among a mixture of conversations and background noises, ignoring other conversations. This effect reveals one of the surprising abilities of our auditory system, which enables us to talk in a noisy place.

The effect can occur both when we are paying attention to one of the sounds around us and when it is invoked by a stimulus which grabs our attention suddenly. For example, when we are talking with our friend in a crowded party, we still can listen and understand what our friend says even if the place is very noisy, and can simultaneously ignore what another nearby person is saying. Then if someone over the other side of the party room calls out our name suddenly, we also notice that sound and respond to it immediately.

It was first described and named by Colin Cherry in 1953. Much of the early work in this area can be traced to problems faced by air traffic controllers in the early 1950s. At that time, controllers received messages from pilots over loudspeakers in the control tower. Hearing the intermixed voices of many pilots over a single loudspeaker made the controller’s task very difficult.

Cherry conducted attention experiments in which subjects were asked to listen to two different messages from a single loudspeaker at the same time and try to separate them. His work reveals that our ability to separate sounds from background noise is based on the characteristics of the sounds, such as the gender of the speaker, the direction from which the sound is coming, the pitch, or the speaking speed.

This phenomenon is still very much a subject of research, in humans as well as in computer implementations, where it is typically referred to as source separation or blind source separation. The neural mechanism in human brains is not yet fully clear.


Rubin’s vase is a famous set of cognitive optical illusions developed around 1915 by the Danish psychologist Edgar Rubin. The illusion generally presents the viewer with a mental choice of two interpretations, each of which is valid. Often, the viewer sees only one of them, and only realizes the second valid interpretation after some time or prompting. When the viewer attempts to simultaneously see the interpretations together, they suddenly cannot see the first interpretation anymore, and no matter how they try they simply cannot encompass both interpretations simultaneously; one occludes the other.

The illusions are useful because they are an intuitive demonstration of the figure-ground distinction the brain makes during visual perception. Rubin’s figure-ground distinction influenced the Gestalt psychologists, who discovered many similar illusions themselves. It involves higher-level cognitive pattern matching in which the overall picture determines its mental interpretation, rather than the net effect of the individual pieces.

Normally the brain classifies images by what surrounds what, establishing depth and relationships. If something surrounds another thing, the surrounded object is seen as figure, and the presumably further away (and hence background) object is the ground, and vice versa. This makes sense, since if a piece of fruit is lying on the ground, one would want to pay attention to the “figure” and not the “ground”.

However, when the contours are not so unequal, ambiguity starts to creep into the previously simple inequality and the brain must begin “shaping” what it sees. It can be shown that this shaping overrides and is at a higher level than feature recognition processes that pull together the face and the vase images. One can think of the lower levels putting together distinct regions of the picture (each region of which makes sense in isolation), but when the brain tries to make sense of it as a whole, contradictions ensue, and patterns must be discarded.



A ganzfeld experiment is a technique used in the field of parapsychology to test individuals for extra sensory perception. It uses homogeneous and unpatterned sensory stimulation to produce an effect similar to sensory deprivation. The deprivation of patterned sensory input is said to be conducive to inwardly generated impressions. The technique was devised by Wolfgang Metzger in the 1930s as part of his investigation into the gestalt theory.

The ganzfeld experiments are among the most recent in parapsychology for testing the existence of and affecting factors of telepathy, which is defined in parapsychology as the paranormal acquisition of information concerning the thoughts, feelings or activity of another person. In the early 1970s, Charles Honorton had been investigating ESP and dreams at the Maimonides Medical Center but became frustrated at the cumbersome nature of the process.

Since the first full experiment was published by Charles Honorton and Sharon Harper in the Journal of the American Society for Psychical Research in 1974, the ganzfeld has remained a mainstay of parapsychological research.

In a typical ganzfeld experiment, a receiver is left in a room relaxing in a comfortable chair with halved ping pong balls over the eyes, having a red light shone on them. The receiver also wears a set of headphones through which white or pink noise is played. The receiver is in this state of mild sensory deprivation for half an hour. During this time a sender observes a randomly chosen target and tries to mentally send this information to the receiver. The receiver speaks out loud during the thirty minutes, describing what he or she can see. This is recorded by the experimenter either by recording onto tape or by taking notes, and is used to help the receiver during the judging procedure.

In the judging procedure, the receiver is taken out of the ganzfeld state and given a set of possible targets, from which they must decide which one most resembled the images they witnessed. Most commonly there are three decoys along with a copy of the target itself, giving an expected overall hit rate of 25% over several dozens of trials.

Between 1974 and 2004, 88 ganzfeld experiments were done, reporting 1,008 hits in 3,145 tests. In 1982, Charles Honorton presented a paper at the annual convention of the Parapsychological Association which summarized the results of the ganzfeld experiments up to that date, and concluded that they represented sufficient evidence to demonstrate the existence of psi. Ray Hyman, a skeptical psychologist, disagreed. The two men later independently analyzed the same studies, and both presented analyses of them in 1985. Honorton thought that the data at that time indicated the existence of psi, and Hyman did not.

Parapsychologists such as Dean Radin and Daryl J. Bem say that ganzfeld experiments have yielded results that deviate from randomness to a significant degree, and that these results present some of the strongest quantifiable evidence for telepathy to date. Critics such as Susan Blackmore and Ray Hyman say that the results are inconclusive, and call for further study before such results can be scientifically accepted.


Holonomic brain theory, originated by psychologist Karl Pribram and initially developed in collaboration with physicist David Bohm, is a model for human cognition that is drastically different from conventionally accepted ideas. Pribram and Bohm suggest a model of cognitive function as being guided by a matrix of neurological wave interference patterns situated temporally between holographic gestalt perception and discrete quantum vectors derived from reward anticipation potentials.

Pribram was originally struck by the similarity of the hologram idea in brain function, along with Bohm’s idea of implicate order in physics, and contacted him for collaboration. In particular, the fact that information about an image point is distributed throughout the hologram, such that each piece of the hologram contains some information about the entire image, seemed suggestive to Pribram about how the brain could encode memories. Pribram was encouraged in this line of speculation by the fact that others had found that the spatial frequency encoding displayed by cells of the visual cortex was best described as a Fourier transform of the input pattern. This holographic idea lead to the coining of the term holonomic to describe the idea in wider contexts than just holograms.

In this model, each sense functions as a lens, refocusing wave patterns either by perceiving a specific pattern or context as swirls, or by discerning discrete grains or quantum units. David Bohm has said that if you take the lenses away, what you are left with is a hologram.

According to Pribram and Bohm, future orientation is the essence of cognitive function, which they have attempted to define through use of the Fourier theorem and quantum mechanical formulae. According to Pribram, the tuning of wave frequency in cells of the primary visual cortex plays a role in visual imaging, while such tuning in the auditory system has been well established for decades. Pribram and colleagues also assert that similar tuning occurs in the somatosensory cortex.

Pribram distinguishes between propagative nerve impulses on the one hand, and slow potentials  or hyperpolarizations that are essentially static. At this temporal interface, he indicates, the wave interferences form holographic patterns.

What the data suggests is that there exists in the cortex a multidimensional holographic process serving as an attractor or point toward which muscular contractions operate to achieve a specified environmental result. The specification has to be based on prior experience of the species or the individual and stored in holographic form. Activation of the stored process involves patterns of muscular contraction guided by basal ganglia, cerebellar, brain stem and spinal cord, whose sequential operations need only to satisfy the target encoded in the image of achievement much as the patterns of sequential operations of heating and cooling must meet the setpoint of the thermostat.

According to this theory, waveforms within the matrix of a distributed system allow fluctuations taking place to create new patterns, and the resulting dynamic potential can then organize new foci of activity oriented to the precipitation of strategic planning and exercise of free will.

In a 1998 interview, Pribram addressed the understanding of cognitive potential, stating that if you get into your potential mode, then new things can happen. But usually free will is conceived of in terms of how many constraints are operating, and we have in statistics a notion of degrees of freedom. I think our will essentially is constrained, more or less. We have so many degrees of freedom, and the more degrees of freedom we have, the more we feel free, and we have freedom of choice.


Gestalt is a German word for form or shape. It is used in English to refer to a concept of wholeness. It proposes that the operational principle of the brain is holistic with self-organizing tendencies, or that the whole is different than the sum of its parts. The classic Gestalt example is a soap bubble, whose spherical shape is not defined by a rigid template or a mathematical formula, but rather it emerges spontaneously by the parallel action of surface tension acting at all points in the surface simultaneously. The Gestalt effect refers to the form forming capability of our senses, particularly with respect to the visual recognition of figures and whole forms instead of just a collection of simple lines and curves.

Early 20th century theorists saw objects as perceived within an environment according to all of their elements taken together as a global construct. This whole form approach sought to define principles of perception, seemingly innate mental laws which determined the way in which objects were perceived. These laws took several forms, such as the grouping of similar objects together. Although Gestalt has been criticized for being merely descriptive, it has formed the basis of much further research into the perception of patterns and objects, and of research into behavior, thinking, problem solving and psychopathology.

Gestalt psychology is a theory of mind and brain that proposes that the operational principle of the brain is holistic, parallel, and analog, with self-organizing tendencies, or that the whole is different than the sum of its parts. Gestalt therapy focuses more on process (what is happening) than content (what is being discussed). The emphasis is on what is being done, thought and felt at the moment rather than on what was, might be, could be, or should be.

Gestalt therapy is a method of awareness, by which perceiving, feeling, and acting are understood to be separate from interpreting, explaining and judging using old attitudes. This distinction between direct experience and indirect or secondary interpretation is developed in the process of therapy. The client learns to become aware of what they are doing psychologically and how they can change it. By becoming aware of and transforming their process they develop self acceptance and the ability to experience more in the now without so much interference from baggage of the past.

The objective of Gestalt therapy, in addition to helping the client overcome symptoms, is to enable him or her to become more fully and creatively alive and to be free from the blocks and unfinished issues that may diminish optimum satisfaction, fulfillment, and growth.

The approach is not the self of the client being helped or healed by the fixed self of the therapist, but the exploration of the co-creation of self and other in the here and now. There is not the assumption that the client will act in all other circumstances as he or she does in the therapy situation. However, the areas that cause problems will be either the lack of self definition leading to chaotic or psychotic behaviour, or the rigid self definition in some area of functioning that denies spontaneity and makes dealing with particular situations impossible.

Some have described Gestalt’s paradoxical theory of change. The paradox is that the more one attempts to be who one is not, the more one remains the same. Conversely, when people identify with their current experience, the conditions of wholeness and growth support change. Put another way, change comes about as a result of full acceptance of what is, rather than a striving to be different.