Mental comparison of visually presented two-digit numbers: a P300 study

Direction effects in number word comparison: an event-related potential study

“…This is in contrast to previous studies, which report an increased P300 for conditions in which the numeric distance was larger rather than smaller ( [8,11], but see [12]). The reverse distance effect in the present study suggests that the mechanism involved in our number comparison task is a serial search mechanism [19].…”

“…In the present study, the response was dependent on the nature of the following prompt and could not be generated at the target number, in contrast to previous studies in which a response was required at the target (e.g. [8][9][10][11][12][13]). Second, in our study, the pairs of number words were clearly defined, and the comparison standard varied per trial, as opposed to many previous studies in which numbers were not presented as pairs and/or a fixed comparison standard was used (e.g.…”

“…Second, in our study, the pairs of number words were clearly defined, and the comparison standard varied per trial, as opposed to many previous studies in which numbers were not presented as pairs and/or a fixed comparison standard was used (e.g. [8][9][10]12]). These differences may have engaged a serial search mechanism in the present task.…”

“…In one study [12], numbers that were larger than an earlier presented fixed standard were indeed responded to faster than number words that were smaller than the standard; however, the ERPs in this and other studies (e.g. [8][9][10][11]13]) did not show any direction effects.…”