The Covid-19 pandemic lockdown had led to unusually mas- sive social isolation that lasted for months around the world. In order to compensate for the poverty of social life, individ- uals are likely to shift their attention from their regular social world to their inner imaginative world during this lockdown pe- riod. Thus, the purpose of this study is to investigate whether intersubject similarity in individuals’ imaginative abilities (i.e., fantasy tendency) is associated with their similarity in affective ratings of the videos they watched, and whether this associa- tion is enhanced during the pandemic lockdown period. We recruited one lockdown group and two post-lockdown groups to test the above hypothesis. During the experiment, partici- pants were asked to watch a series of videos covering a wide range of topics, and then they were asked to complete several affective appraisal ratings (e.g., liking or feeling of resonance) of each video. We then used intersubject representational similar- ity analysis (ISRSA) to map the intersubject similarity in their fantasy tendency onto their similarity in the affective appraisal ratings. Our results showed that those who were more simi- lar in their fantasy scores also showed more similarity in their affective appraisals of videos. Most importantly, this fantasy- appraisal association was particularly strong in the lockdown group, but rather weak in the post-lockdown groups. Our find- ings suggest that individual differences in their imaginative abil- ities would become a crucial factor influencing how individuals appraise their inner world during social isolation. The current study may provide an example for policymakers on how to as- sess the impact of social isolation as we may face another wave of pandemics in the future.