Abstract: The perceived duration of a specific event has been shown to be influenced by other dimensions of the very same event. In a previous experiment participants were presented with two stimuli consisting of small blue dots appearing and disappearing dynamically on the screen for different periods of time. Participant’s task was to judge whether the second stimulus was shorter/longer (time condition) or consisted of fewer/more dots (numerosity condition) than the first stimulus. Using a Maximum Likelihood Estimation (MLE) procedure we estimated, for each participant separately, to what extent temporal and numerical information was taken into account in making judgements on either time or numerosity. Results showed that judgements on time were more likely to be affected by numerosity, while numerosity judgements were relatively resilient to temporal interferences. However, we found large individual differences in the magnitude of these interference effects (i.e., some participants relied almost exclusively on information of the relevant dimension, thus showing no or weaker interference effects). In the current study, we will test how stable these congruency effects are over time and over different task versions. Participants attended two sessions separated by six to eight days. During each session participants performed the dynamic magnitude task as described above, and a static version of the magnitude task (i.e., dots do not appear and disappear, but all dots are presented from onset to offset of the stimulus). In addition, participants performed a numerical Stroop task during Session 1, and a simple duration discrimination task during Session 2. This study-design enables direct comparison of MLE estimates over time (session one vs. session two) and between tasks (dynamic vs. static magnitude task). Further, we will assess whether magnitude of time-numerosity interference effects is related to effects in other interference and temporal judgement tasks (numerical Stroop and duration discrimination).