Caffeine Improves Left Hemisphere Processing of Positive Words

Abstract

A positivity advantage is known in emotional word recognition in that positive words are consistently processed faster and with fewer errors compared to emotionally neutral words. A similar advantage is not evident for negative words. Results of divided visual field studies, where stimuli are presented in either the left or right visual field and are initially processed by the contra-lateral brain hemisphere, point to a specificity of the language-dominant left hemisphere. The present study examined this effect by showing that the intake of caffeine further enhanced the recognition performance of positive, but not negative or neutral stimuli compared to a placebo control group. Because this effect was only present in the right visual field/left hemisphere condition, and based on the close link between caffeine intake and dopaminergic transmission, this result points to a dopaminergic explanation of the positivity advantage in emotional word recognition.

Individual differences in emotion word processing: A diffusion model analysis

“…The negative correlation of H-F RT differences with the number of blinks suggests that greater differences in RTs were related to a higher blink rate. Taking into account the results of Kuchinke and Lux (2012), where an indirect enhancement of dopamine levels in the striatum was achieved that resulted in a processing advantage for positive words, it seems likely that in the present study a higher dopamine availability at the brain level (as indicated by blink rate) had a facilitatory influence on processing of positive stimuli, in this case happy words. This assumption gains additional support from a study by Epstein et al (2006), who found less striatal activation in response to positive words in a group of depressed subjects compared to healthy controls.…”

“…Because a top-down influence of the associative structure of to-be-processed items is controversially discussed in case of the LDT (e.g., Kuchinke et al, 2005), the density and similarity of valenced material alone might not be sufficient to explain a positivity advantage. Accordingly, Kuchinke and Lux (2012) were able to provide some evidence linking the positivity advantage in word recognition to dopaminergic transmission and the specificity of the language-processing left-brain hemisphere. An emotion effect was also evident in error rates replicating the findings of Briesemeister et al (2011a) of larger error rates for fear-related compared to happy and neutral words.…”

“…Recent evidence suggests not only that positive words are processed faster than negative and neutral words but also that lexical access (i.e., the time it takes until a word is identified) is fastest in positive words (Kissler & Herbert, 2013). This facilitatory effect is also reflected in accuracy data where fewest errors are observed for positive words (Briesemeister et al, 2011a;Kousta et al, 2009;Kuchinke & Lux, 2012). While these findings based on positive valence seem reliable across studies, findings regarding negatively valenced words are less homogeneous.…”

“…Similarly, based on findings in emotion word recognition, Kuchinke and Lux (2012) discussed that observed hemispheric differences in implicit emotion processing might depend on brain dopamine levels. Thus, the availability of dopamine seems to be a reasonable factor underlying different emotional responses and individual differences in emotion processing.…”

The effect of black tea on human cognitive performance in a cognitive test battery

“…It is presumable that drinking of BT accelerates the consolidation [36] and retrieval of memory. The memory traces could be stabilized during the experimental sessions which helped BT consumers to retrieve the words [42]. A revious study [17] suggest that caffeine alters neuronal activity in the DLPFC (dorsolateral Pre-Frontal Cortex) during performance on a working memory task [38].…”