When gratitude and cooperation between friends affect inter-brain connectivity for EEG

Abstract

Background: Recently several studies in the psychological and social field have investigated the social function of gift exchange as a useful way for the consolidation of interpersonal and social relationships and the implementation of prosocial behaviors. Specifically, the present research wanted to explore if gift exchange, increased emotional sharing, gratitude and interpersonal cooperation, leading to an improvement in cognitive and behavioral performance. In this regard, neural connectivity and cognitive performance of 14 pairs of friends were recorded during the development of a joint attention task that involved a gift exchange at the beginning or halfway through the task. The moment of gift exchange was randomized within the pairs: for seven couples, it happened at task beginning, for the remaining seven later. Individuals' simultaneous brain activity was recorded through the use of two electroencephalograms (EEG) systems that were used in hyperscanning.

Results: The results showed that after gift exchange there was an improvement in behavioral performance in terms of accuracy. For what concerns EEG, instead, an increase of delta and theta activation was observed in the dorsolateral prefrontal cortex (DLPFC) when gift exchange occurred at the beginning of the task. Furthermore, an increase in neural connectivity for delta and theta bands was observed.

Conclusion: The present research provides a significant contribution to the exploration of the factors contributing to the strengthening of social bonds, increasing cooperation, gratitude and prosocial behavior.

Keywords: Cooperation; DLPFC; EEG; Emotions; Gratitude; Inter-brain connectivity.

Fig. 1

The figure shows the experimental procedure. Two different procedures for the cooperative task were performed. The first, order 1, is divided in: block 1 (a control condition), gift exchange (image retrieved from pixabay), block 2 and block 3. The second, order 2, is divided in: block 1, block 2, gift exchange (image retrieved from pixabay), and block 3. Each block was composed by 25 trials and after each trial members of the couple received a feedback on their cooperation level

Fig. 2

a The figure shows the percentage of performance accuracy (ACC) for order 1 and order 2 for block 1, block 2 and block 3. b The figure shows the questionnaire responses about perceived tuning and perceived collaboration and gratitude before and after gift exchange

Fig. 3

a Histograms of delta values (d1 and d2) in DLPFC area for order 1 and order2. b Histograms of theta values (d1 and d2 values) in DLPFC area for order 1 and order 2. c Delta power representation (d1 and d2 values) for order 1 and 2. The red color represents the areas in which compare an increase of delta d1 and d2 values. d Theta power representation (d1 and d2 values) for order 1 and 2. The figure shows an increase of theta in DLPFC area for order 1 than order 2. The blue color represents the areas in which compare an increase of theta d1 and d2 values. e Histogram of alpha values (d1 values) in DLPFC area for order 1 and order 2. f Histogram of alpha values (d2 values) in DLPFC area for order 1 and order 2

Fig. 4

a Histograms of delta values (r coefficient) in DLPFC area for order 1 and order 2. b Histograms of theta values (r coefficient) in DLPFC area for order 1 and order 2. c Graphical representation of delta R coefficient distribution (brain connectivity), represented by dots within the cortical maps. Specifically, the figure shows an increase of delta brain connectivity in DLPFC area for order 1 and 2. d Graphical representation of theta R coefficient distribution (brain connectivity), represented by dots within the cortical maps. Specifically, the figure shows an increase of theta brain connectivity in DLPFC area for order 1 and 2