1993). Reduced N4 amplitude of the difference waveform between primed and unprimed words has been reported (Nixon et al., 2002). Similarly, in a recent semantic decision task there was less attenuation of N400 amplitudes to primed words when compared to unprimed words in alcoholics, a phenomenon that was intact in the controls (Porjesz et al., 2002b; Roopesh et al., 2010) (Fig. 23.4). Significant group differences were not seen for latency; however all subjects had slower reaction time for unprimed words compared to primed words, but significantly less reaction time savings between the unprimed and primed condition was noted for alcoholics. This lack of attenuation for the primed word suggests a deficiency of semantic priming process in the alcoholics where the expectancy for the second word of the antonym pair is not adequately generated. Similarly, young adult male HR offspring from alcoholic families manifested a lack of N400 attenuation, indicating deficits in semantic expectancy and post lexical semantic processing which may be present prior to alcohol dependence (Roopesh et al., 2009) (Fig. 23.4). These studies suggest that alcohol-dependent individuals and those at risk suffer from subtle impairments indicative of a reduced efficiency in resource optimization.
