What is 'programming thinking'? In a study, first year students were interviewed on their understanding of what learning to program means. Many students talked about learning to program in terms of learning a special way to think, different from other subjects studied. Many of these students had problems in describing what this special way to think included. The analysis of the interviews revealed some features of this thinking, as expressed by the students. In this paper we discuss and analyse 'programming thinking' using phenomenography as our research approach [7]. Our results are coherent with Hazzan's research on the learning theory 'process-object duality' [4], but points to problems in learning of object-oriented programming not indicated in 'process-object duality'. In comparing the results form our own study with this learning theory, we discuss what this might mean in learning object-oriented programming.