[an error occurred while processing this directive] Experiment 12 Depth 90 meters

Experiment 12.
Author / experimenter : drs J. P. Krol (diver / experimental neuropsychologist).


Purpose of the experiment was to investigate the influence of mental load without information handling on information handling capacity.

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It was also intended to demonstrate how the BCG with LDSR-unit could be used as a research tool in an important research field, notably the adaptation of man to submarine conditions with extremely high pressures.

This type of research is done in wet decompression tanks where most conditions of extremely deep dives can be simulated.

In this field a great demand exists for on-line human performance evaluation tools, since performance is the ultimate criterion deciding the acceptability of working conditions ( when certain physiological values are not exceeded).

Especially when cerebral malfunction may be suspected ( as is the case in hyper baric research), refined performance criteria give the earliest symptoms.


Material and methods.

A wet decompression tank was used tested to an equivalent of 450 ft of water depth.

The cylindrical tank has a diameter of 11 ft. The lower part contains 10 ft of water, separated from the dry section by a metal grid with an opening through which the diver can descend.

In the dry part, the medical staff and responsible diving officer are seated on benches fixed against the cylinder wall.

They can walk around on the meta1 grid covering the wet part.

In the dry and wet part portholes allow observation from outside.

The binary choice generator was placed outside the tank, in the tank control room.

It was also connected to a pen-writer giving an immediate and continuous record of BCG performance, notably response interval times.

Performance was also scored on electromagnetic tape.

Experimental treatments consisted of three pressure levels, viz. 0 ft, 210 ft, and 270 ft.

It was the first time in the Netherlands, human subjects were subjected to pressures in access of 150 ft and it was decided that if BCG performance would be clearly deteriorated at the 210 ft-level no further increase in pressure would be made.

This decision would be made by the physician in the tank control room, who was operating the BCG.

The senior physician was supervising inside the tank but allowance had to be made for a possible incapacitation at these high pressures with which we had no experience.

Hence the responsibility shift at the 210 ft with the BCG performance as common sense criterion.

Three subjects performed the BCG task :
1) The senior diving officer, also responsible for the divers safety.
2) The author.
3) A medical orderly.

Subjects 1 and 3 were in the dry compartment, subject 2 (the author) was submerged until after the 210 ft. samples had been taken and in the dry at the 270 ft level.

This was a safety measure since it was not known what each individuals reactions would be under a pressure of ten atmosphere (air).



Figure gives information handling capacity as a function of pressure level.
scien22.gif (2829 bytes)

The individual performance traces and some apparatus used are shown in 13 apparatus and registrationsunder :  experiment 12



The results clearly show a performance deterioration with increasing pressure.

Yet it is also clear that the change is not dramatic, suggesting adequate information handling capacity at all levels.

The results do not show that at the higher pressure levels subjects possibly had to concentrate much more on the task.

The authors' subjective experience was that at the 270 ft level he had to put an extreme effort into concentration, with a funnel vision, focused on the light stimulus.

The experiment has demonstrate the usefulness off using BCG with LDSR- unit for getting an on-line performance indication of a submerged diver to personnel outside the pressure area.

This experiment was repeated with 14 frogmen after clearence from the Admiral.

See : 13. apparatus and registrations,
experiment 12-follow-up.

Validation of constructs II  "Main Page"

Copyright J. P. Krol ©