A handful of studies have in fact investigated the cognitive-affective mechanisms associated with the 5-HTTLPR. Beevers et al. (Beevers, Gibb, McGeary, & Miller, 2007) reported that depressed inpatients with at least one short allele exhibited more cognitive bias for anxiety-related words than those with two long alleles. Additionally, other studies have suggested that short allele carriers may more intensely process fear-related emotional stimuli (Bertolino et al., 2005; Surguladze et al., 2008; Osinsky et al., 2008), while Fox and colleagues (Fox, Ridgewell, & Ashwin, 2009) reported that individuals with the l/l genotype evidenced bias towards positive pictures and avoidance of threat related images. A study with adolescents revealed a linear relation between presumed serotonin availability (based on genotype) and and the magnitude of attention towards angry and happy faces (Perez-Edgar et al., 2010). These studies were done with relatively small samples that are more typical of cognitive neuroscience studies rather than the traditionally larger genetic studies.
