The similarity, attraction, and compromise effects warrant specific investigation in multi-attribute decision making. To examine these effects concurrently, we assigned 145 undergraduates to three context effect conditions. They were requested to solve 20 hypothetical purchase problems that had three alternatives described along two attribute dimensions. We measured their choices, confidence ratings, and response times. We found that adding the third alternative had significant effects for choice proportions and confidence ratings in all three conditions. The attraction effect was more prominent than the other two effects with regard to choice proportions. The compromise effect condition yielded low confidence ratings and long response times, although the choice proportion was high for the third alternative. These results indicate that the mutual relationship among choice proportions, confidence ratings, and reaction times requires theoretical investigation.