We examined (a) how emotional attachment to a choice option as indexed by state-related changes in electroencephalographic (EEG) asymmetry over the prefrontal cortex and electrodermal activity predicts choices and mediates the endowment effect and (b) the emotional-motivational responses to trade-off choices. Thirty-eight participants made choices between three 4-product packages, in which the frequency of each of the products varied. Greater relative left frontal activation and high peak skin conductance level (SCL) elicited by a previously selected choice option predicted a stronger endowment effect, suggesting that approach motivation and emotional attachment mediate the endowment effect. Not selecting a choice option with high emotional attachment elicited relatively greater right hemisphere activation, supporting also the role of loss aversion in the endowment effect. In addition, high trade-off difficulty was associated with increased withdrawal motivation (or less approach motivation) and negatively valenced arousal. We conclude with a discussion of practical implications of our findings. (C) 2016 Published by Elsevier B.V.