This paper investigates the impact of irrelevant location information on performance in visual choice-reaction tasks, focusing on the Simon effect and the spatial Stroop effect. The authors review empirical findings and theoretical explanations from these two domains, highlighting how stimulus location influences performance even when it is uninformative to the correct response. Key factors include response modality, relative timing with respect to relevant information, spatial coding, and attention allocation. The most promising models suggest that response selection is influenced by the strength of association between irrelevant stimulus information and the response, as well as the temporal overlap of response activations. The paper discusses the role of stimulus location in visual information processing, the nature of the Simon effect, and the spatial coding of responses. It also explores the contributions of attention shifting and relative processing speed to the Simon effect. The findings suggest that the Simon effect is primarily due to response-selection processes, with spatial coding and attentional orienting playing crucial roles.This paper investigates the impact of irrelevant location information on performance in visual choice-reaction tasks, focusing on the Simon effect and the spatial Stroop effect. The authors review empirical findings and theoretical explanations from these two domains, highlighting how stimulus location influences performance even when it is uninformative to the correct response. Key factors include response modality, relative timing with respect to relevant information, spatial coding, and attention allocation. The most promising models suggest that response selection is influenced by the strength of association between irrelevant stimulus information and the response, as well as the temporal overlap of response activations. The paper discusses the role of stimulus location in visual information processing, the nature of the Simon effect, and the spatial coding of responses. It also explores the contributions of attention shifting and relative processing speed to the Simon effect. The findings suggest that the Simon effect is primarily due to response-selection processes, with spatial coding and attentional orienting playing crucial roles.