Responding to emotional scenes: effects of response outcome and picture repetition on reaction times and the late positive potential.

Processing the motivational relevance of a visual scene and reacting accordingly is crucial for survival. Previous work suggests the emotional content of naturalistic scenes affects response speed, such that unpleasant content slows responses whereas pleasant content accelerates responses. It is unclear whether these effects reflect motor-cognitive processes, such as attentional orienting, or vary with the function/outcome of the motor response itself. Four experiments manipulated participants' ability to terminate the picture (offset control) and, thereby, the response's function and motivational value. Attentive orienting was manipulated via picture repetition, which diminishes orienting. A total of N = 81 participants completed versions of a go/no-go task, discriminating between distorted versus intact pictures drawn from six content categories varying in positive, negative, or neutral valence. While all participants responded faster with repetition, only participants without offset control exhibited slower responses to unpleasant and accelerated responses to pleasant content. Emotional engagement, measured by the late positive potential, was not modulated by attentional orienting (repetition), suggesting that the interaction between repetition and offset control is not due to altered emotional engagement. Together, results suggest that response time changes as a function of emotional content and sensitivity to attention orienting depends on the motivational function of the motor response.