Inert gas narcosis and the encoding and retrieval of long-term memory.
BACKGROUND
Prior research has indicated that inert gas narcosis (IGN) causes decrements in free recall memory performance and that these result from disruption of either encoding or self-guided search in the retrieval process. In a recent study we provided evidence, using a Levels of Processing approach, for the hypothesis that IGN affects the encoding of new information. The current study sought to replicate these results with an improved methodology.


METHODS
The effect of ambient pressure (111.5-212.8 kPa/1-11 msw vs. 456-516.8 kPa/35-41 msw) and level of processing (shallow vs. deep) on free recall memory performance was measured in 34 divers in the context of an underwater field experiment.


RESULTS
Free recall was significantly worse at high ambient pressure compared to low ambient pressure in the deep processing condition (low pressure: M = 5.6; SD = 2.7; high pressure: M = 3.3; SD = 1.4), but not in the shallow processing condition (low pressure: M = 3.9; SD = 1.7; high pressure: M = 3.1; SD = 1.8), indicating IGN impaired memory ability in the deep processing condition. In the shallow water, deep processing improved recall over shallow processing but, significantly, this effect was eliminated in the deep water.


CONCLUSIONS
In contrast to our earlier study this supported the hypothesis that IGN affects the self-guided search of information and not encoding. It is suggested that IGN may affect both encoding and self-guided search and further research is recommended.
Department of Psychology, University of Winchester, Hampshire, UK. wendy.kneller@winchester.ac.uk
Wendy
W
Kneller
Department of Psychology, University of Winchester, Hampshire, UK.
Malcolm
M
Hobbs
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D004242:Diving / Q000502:physiology / Q000523:psychology*; D006801:Humans; D007222:Inert Gas Narcosis / Q000503:physiopathology / Q000523:psychology*; D008297:Male; D057567:Memory, Long-Term / Q000502:physiology*; D008606:Mental Processes / Q000502:physiology; D011939:Mental Recall / Q000502:physiology*; D008875:Middle Aged; D009483:Neuropsychological Tests; D055815:Young Adult