Binary information is prevalent in the environment. In this
study, we examined how people process repetition and
alternation in binary sequences. Across four paradigms
involving estimation, working memory, change detection, and
visual search, we found that the number of alternations is
under-estimated compared to repetitions (Experiment 1).
Moreover, recall for binary sequences deteriorates as the
sequence alternates more (Experiment 2). Changes in bits are
also harder to detect as the sequence alternates more
(Experiment 3). Finally, visual targets superimposed on bits
of a binary sequence take longer to process as alternation
increases (Experiment 4). Overall, our results indicate that
compared to repetition, alternation in a binary sequence is
less salient in the sense of requiring more attention for
successful encoding. The current study thus reveals the
cognitive constraints in the representation of alternation and
provides a new explanation for the over-alternation bias in
randomness perception.