**Have any data been collected for this study already?** No, no data have been collected for this study yet. **What is the main question being asked or hypothesis being tested in this study?** Prior studies have proved a self-prioritization-effect in perceptual matching tasks, in which participants were asked to react on matching or mismatching pairs that represented “self“, “friend“ and “stranger“ (Sui, Humphreys & He, 2012). It has also been shown that the reaction time to the matching pairs of “friend“ were shorter than the reaction time on matching pairs with “stranger“. Further research showed also faster reaction times in perceptual matching tasks towards the own group compared to a neutral group or a rival group (Enock, Sui, Hewstone & Humphreys, 2018). Our aim is to test if this in-group prioritization is also found, when two partners that were unknown to each other before have solved a task together before solving the perceptual matching task individually. We plan therefore to make team-membership salient for the half of the participants (in-group). The other half of the participants should solve the perceptual matching task after having induced an individual self-representation (individual). In both conditions – in-group and individual – two participants are invited to complete the perceptual matching task on the same time on two separate places. Matching and mismatching pairs in the perceptual matching task should consist of four labels “me“, “partner“, “acquaintance“ and “stranger“ and of abstract symbols (circle, triangle, cross and square). Salience of social closeness will be tested three times: Before inducing social identity, after the first block of the perceptual matching task and at the end. The main focus of our study is to investigate the self-prioritization-effect and its modulation, the partner-prioritization-effect. A self-prioritization-effect (SPE) is expressed by a faster and more accurate reaction to self-relevant matching trials compared to non-self-relevant matching trials. We expect to find a partner-prioritization-effect (PPE), which can be determined by a difference in response times and error rates between partner-relevant matching trials compared to neutral matching trials (e.g. stranger or acquaintance). **Describe the key dependent variable(s) specifying how they will be measured.** We will measure reaction times and error rate. **How many and which conditions will participants be assigned to?** There are three conditions. First social closeness (in-group vs. individual) as a between-subjects-factor, second label (“me” vs. “partner” vs. “acquaintance” vs. “stranger”) as a within-subjects-factor and third match of the symbol-label combination (matching vs. non-matching) as a within-subjects-factor. There are four different labels and four symbols, resulting in 16 combinations in total of which 4 match as a pair and 12 mismatch. Each combination will be presented to each participant – half of the presented pairs of label and symbol will be matching, half mismatching. The order of conditions in each block will be randomized. **Specify exactly which analyses you will conduct to examine the main question/hypothesis.** In the following analyses we will only concentrate on the matching condition in which we expect to find all effects (SPE and PPE). Mean reaction times and error rates as dependent variables will be analyzed using 2 (social closeness: in-group vs. individual) x 4 (label: me vs. partner vs. acquaintance vs. stranger) repeated measures ANOVA with social closeness as a between- subjects-factor and label as a within-subjects-factor. First, we expect a significant main effect of the social closeness, suggesting faster and more accurate responses in the in-group condition than in the individual condition. Second, we also expect a significant main effect of the label, suggesting different response times and errors according to the label. Third, we expect a significant interaction effect, showing that the effect of the label is different in the in-group and the individual condition. We will conduct Post-hoc tests to identify the self-prioritization-effect and partner-prioritization-effect. First, we compare reaction times and error rates for the labels “acquaintance” and “stranger”. If they do not differ significantly, we will form a neutral condition out of them. We expect a significant self-prioritization-effect, showing significantly faster and more accurate responses to the label “me” compared to the neutral condition. We expect a significant partner-prioritization-effect, showing significantly faster and more accurate responses to the label “partner” compared to the neutral condition. We also expect that the SPE is significantly larger than the PPE. To test this hypothesis, we will implement a t-test between two dependent groups comparing the first difference (SPE) with the second difference (PPE). At last, we will examine if the PPE is strong in the in-group condition but significantly reduced in the individual condition. We expect that the self-prioritization-effect will not significantly interact with social closeness. On the other hand, we assume that the partner-prioritization-effect will significantly interact with social closeness. **Any secondary analyses?** If the effect of social closeness is not significant, we would conduct our data-analysis block by block. The possible time limitation of the effect could be one possible explanation for its weakening in the course of the blocks. How many observations will be collected or what will determine sample size? No need to justify decision, but be precise about exactly how the number will be determined. After a practice block with 48 trials the participant passes through the perceptual matching task in 3 blocks à 168 trials, in total 504 trials. We will recruit 60 participants who are students of the University of Hildesheim and will participate for course credit, as well as other interested persons. Due to that both conditions of social closeness will be presented to 30 participants. Based on previous experiments with this or comparable paradigms, this sample size seems reasonable. **Anything else you would like to pre-register? (e.g., data exclusions, variables collected for exploratory purposes, unusual analyses planned?)** The combinations of labels and symbols will be counterbalanced. Each symbol is crossed with all labels, resulting in 16 trials. The matching trials are triple weighted to have a matching non-matching ratio of 50:50 = 24 trials. Three experimental blocks with 7 x 24 trials result in a total of 504 trials, which are presented to the participant. 48 practice trials will be excluded from the analysis. Subjects with extreme values as well as many missing values or very frequent errors are excluded from analysis. Response times below 200 ms will be removed and according to the Tukey-criterion. **References** Sui, J., Humphreys, G. & He, X. (2012). Perceptual effects of social salience: Evidence from self-prioritization effects on perceptual matching. Journal of Experimental Psychology: Human Perception and Performance, 38 (5), 1105–1117. Enock, F., Sui, J., Hewstone, M. & Humphreys, G. (2018). Self and team prioritisation effects in perceptual matching: Evidence for a shared representation. Acta Psychologica, 182, 107-118.