Research suggests that promoting environmental responsibility is often more effective using subtle interactive feedback rather than standard signage. To investigate this, a psychologist conducted an observational study in a busy central train station, monitoring commuters' disposal of disposable coffee cups into two recycling bins. One bin was equipped with a sensor that played a pleasant chime when a cup was deposited (an 'audio nudge'), whereas the other bin was standard and silent.

Using event sampling, recordings were made each time an individual correctly deposited a cup into either bin during a continuous three-hour morning commute period from 7:00 am to 10:00 am. The data showing the frequency of bin use is presented in the table below.

Table 1: Frequency of recycling bin use by commuters with and without luggage