Ben LW/Flickr
Source: Ben LW/Flickr

Do we actually know what is happening in the mind when we are physically and socially isolated?  Originally created in the 1950s to study consciousness, sensory deprivation tanks may provide some insight.

Isolation Chambers and Sensory Processing

Also known as an “isolation tank” or “float tank”, a typical sensory deprivation tank is a dark windowless box large enough to accommodate an adult.  The customer, naked or with minimal clothes, lies flat in a lukewarm saline solution that creates a “floating” sensation.  The extreme darkness makes it nearly impossible to see anything, including your own hand, in front of your face.  There is no smell, taste, or sound (other than the sounds you make).  The philosophy behind the design is to minimize as much sensory stimulation as possible.  In essence, one cannot hear, taste, touch, smell, or see.

Flotation Tanks/Flickr
Source: Flotation Tanks/Flickr

When incoming sensory information is minimized or eliminated the effects can be unnerving. 

From the standpoint of neuropsychology, the human brain was designed to process sensory information.  At the most basic level, the mind processes information coming in through our five sensory modalities (i.e., taste, touch, smell, hearing, and vision).  In other words, our brains were shaped by evolution to process incoming stimuli.  That information is then used to inform behavioral decisions that will help guide us through the world.  Human are the most social creatures on the planet, thus many of those decisions involve navigating through the social world.

Ancestral Brains, Modern Problems

From an evolutionary perspective, the adapted mind is just not designed to handle conditions of modern isolation.  For at least five million years, humans have faced adaptive problems posed by our social environment (e.g., decoding emotional expressions, communicating internal mental states to others, and detecting cheaters in social interactions, etc.). Thus we have shaped a psychological repertoire that includes mechanisms designed to solve those social problems.

The hominid mental tool kit is equipped with many solutions to social problems, but nothing that was designed to solve total physical and social isolation.  This, in turn, gives way to the development and expression of many of the mental illnesses we see in solitary confinement units in prisons throughout the world.

Prisoner in the Hole

Solitary confinement is currently used in criminal justice systems worldwide as means to manage disruptive inmates.  Generally speaking, the method involves placing an inmate in a secluded cell with little or no social interaction.  Although widely practiced, there is mounting evidence of negative psychological outcomes.  Social isolation can lead to mental conditions including depression, anxiety, increased arousal, and self-harm.

In Dr. Phil Zimbardo’s infamous 1971 Stanford Prison Experiment, one of the volunteer participants randomly assigned to the inmate role, prisoner 819, refused to eat his sausages when ordered to do so by the guards on duty.  He was

Jhnon Doe/Flickr
Source: Jhnon Doe/Flickr

subsequently sent to the “hole” - a makeshift holding cell that was in reality a closet – as punishment for his actions.  As leader of the prisoner rebellion, the guards felt it necessary to assert their authority on him to quickly end the insurrection.  Eventually, prisoner 819 broke down emotionally and had to be reminded by Dr. Zimbardo himself that this was only an experiment.

Of course, variables such as length of isolation, age, and preexisting mental conditions should be included as psychological health risk factors in any discussion of the effects of solitary confinement.  There is almost certainly a cumulative effect of repeated social isolation throughout life that may impact young and older persons differently.  The evolutionary psychology model of solitary confinement emphasizes the “lack of fit” between the likely environment our ancestors faced and current features of the modern world. 


Glancy, G. D., & Murray, E. L. (2006, October). The psychiatric aspects of solitary confinement. Victims & Offenders, 1(4), 361-368. doi:10.1080/15564880600922091

Haney, C., Banks, W. C., & Zimbardo, P. G. (1973). A study of prisoners and guards in a simulated prison. Naval Research Review, 30, 4-17.

Kaba, F., Lewis, A., Glowa-Kollisch, S., Hadler, J., Lee, D., Alper, H., Selling, D., MacDonald, R., Solimo, A., Parsons, A., & Venters, H. (2014). Solitary confinement and risk of self-harm among jail inmates. American Journal of Public Health, 104(3), 442.

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