Ignoring or withholding a response from a stimulus causes it to become affectively devalued. Leading accounts posit that this is due to negative affect elicited by neurocognitive inhibition when it is applied to resolve conflict from distracting or otherwise inappropriate stimulus/response representations. Other research, however, suggests that stimulus/response conflict may itself elicit negative affect and devalue stimuli, raising questions about whether effects previously attributed to inhibition may instead reflect the emotional impact of conflict, per se. To address this, we measured affective ratings of art-like patterns that previously appeared on critical trials of a task-switching paradigm (ABA vs. CBA task sequences) known for its capacity to distinguish behavioural effects of inhibition and conflict. Stimuli from the ABA-sequence experimental condition showing behavioural evidence of backward inhibition (n-2 repetition costs) received more negative ratings than those from the CBA-sequence control condition. This stimulus-devaluation effect was not impacted by the level of conflict associated with high uncertainty or low uncertainty about upcoming task order. Moreover, the response-time index of inhibition was larger on ABA trials in which the associated stimuli later received negative ratings than on trials preceding relatively positive ratings. Inhibition therefore appears to have negative affective consequences that exceed any emotional impact of conflict, with fluctuations in inhibition linked to subsequent stimulus evaluations.