No–No–No 200.40 204.73 Ob–No–No 206.58 217.37 No–Ob–No 201.21 215.64 Ob–Ob–No 205.73 222.67 GRIFFITHS AND TIPPER Table 1. Mean reach heights for Experiments 1 and 2 Experiment 1 2 Workspace Separate Shared Note: Heights in mm. Ob = obstacle. No = no obstacle. started with their eyes closed, opening them upon instruction. After the ﬁrst participant had ﬁnished their reach, the participants observed the exper- imenter slide the tablet with the blocks on it across to the second participant. They were then instructed to close their eyes while the experimenter arranged the objects for the next trial. The partici- pants were then given the instruction to open their eyes, and the second person executed their reach. Results A number of trials were removed due to collisions or recording failure and where participants had failed to open their eyes on the previous observation trial (1.36%). Results are shown in Table 1. As with the separ- ate-workspace experiment, there was a signiﬁcant effect of a participant’s own previous reach on their current reach: N – 2, F(1, 15) = 22.49, p , .001. However, in stark contrast to the previous exper- iment, there was a signiﬁcant effect of observing the other participant’s reach over an obstacle: N – 1, F(1, 15) = 5.83, p = .029. There was no inter- action between N – 1 and N – 2, F(1, 15) = 2.64, p = .125. Further planned (two-tailed) contrast t tests, comparing the baseline (No–No–No) to con- ditions with obstacles at N – 2 and N – 1, revealed sig- niﬁcant effects in both cases: Ob–No–No, t(15) = 4.86, p , .001; No–Ob–No, t(15) = 3.65, p = .001. In addition to the analysis above, the results from the shared-workspace Experiment 2 were compared to those from the separate-workspace Experiment 1 in a mixed two-way analysis of var- iance (ANOVA). This revealed a signiﬁcant inter- action between N – 1 (obstacle priming by observation) and experiment, F(1, 15) = 4.50, p = .042—that is, the N – 1 effects signiﬁcantly dif- fered between experiments. There was no 1246 THE QUARTERLY JOURNAL OF EXPERIMENTAL PSYCHOLOGY, 2012, 65 (7) signiﬁcant interaction between N – 2 and exper- iment, F(1, 15) = 1.96, p = .172—that is, no sig- niﬁcant difference in the priming of participants by their own previous reaches between experiments. There were no other signiﬁcant interactions. Because the key issue is the effect of observing another person’s reaching action on the subsequent response of a participant, more detailed analysis of the N – 1 between-person priming effects was undertaken where points along the reach trajectory were analysed. Figure 3, Panel A shows the reach trajectories from the separate-workspace trials of Experiment 1 where there were no obstacles on previous trials (No–No–No) and an obstacle on the previous N – 1 trial (No–Ob–No). Panel B shows this data for the shared-workspace con- ditions (Experiment 2). These ﬁgures show the qualitative distinction between the experiments. The vertical lines show the points of comparison along the trajectories where the analysis was carried out in a 2 (obstacle condition) × 7 (location: 7 loci at 5-cm steps) ANOVA. For the separate-workspace Experiment 1, there was no N – 1 effect when observing another person’s reach over an obstacle, F(1, 14) = 0.17, p = .684. Furthermore, there was no interaction with dis- tance, indicating that there was no priming across the whole of the reach. In sharp contrast, the shared-workspace Experiment 2 showed a signiﬁ- cant effect of N – 1, F(1, 14) = 6.90, p = .020. Again this did not interact with distance, demon- strating that there was a consistent N – 1 priming effect throughout the analysed regions of the reach. Discussion The results are clear. In terms of the participant’s own priming effect (N – 2), there is clear evidence that reaching over an obstacle results in a more