Abstract: Evidence for Spatial-Temporal associations of response codes (STEARC) effect reports faster reaction times to short/long durations with the left/right hand, respectively. The cognitive origin of the STEARC effect is on debates: the visuospatial account and the verbal account. According to visuospatial coding, time is mentally represented along a continuous left-to-right-oriented representational line with short/long durations located on the left/right side of the mental time line, respectively. With respect to verbal coding, time–space interactions would result from an association between the verbal categorical concepts “short” and “left” as well as “long” and “right”. To determine whether participants were biased towards verbal coding mechanisms as the SNARC effect that exists in number and space, in Experiment 1, using the similar task as that in Georges (2015), we not only instructed participants to respond to a certain verbal label irrespective of its physical side (verbal instruction condition), but also required them to respond to either the left or right physical response side regardless of the displayed verbal labels (spatial instruction condition).To dissociate the confound of both coding mechanisms (e.g., faster left-sided responses for short duration could result from an association either between the verbal concepts “short” and“left” or between short duration and the left side of physical space), we randomly varied the position of the verbal labels “Left” and “Right” to appear on the left or right physical response sides. We created verbal congruency, referring to the congruency between the magnitude of the presented duration and the verbal label of the participant’s response. The physical congruency refers to the congruency between the magnitude of the presented duration and the physical side of the participant’s response. Participants were instructed to respond to the verbal labels regardless of their physical side of appearance (e.g., click on the verbal labels “Left”/“Right” for small/large numbers, respectively) or respond on the left/right physical response side for short/long durations, respectively, regardless of the displayed verbal labels. Median RTs were subjected to 2× 2×2 repeated measures analysis of variance (ANOVA) including instruction condition (verbal, spatial),physical congruency, and verbal congruency as within-subject factors. Another statistical approach is regression analysis. Two different types of STEARC effects–visuospatial SNARC effect and a verbal–spatial SNARC effect were calculated for each instruction condition. The result revealed the predominance of verbal coding under verbal task instructions. However, this pattern changed under spatial instruction condition, in which visuospatial STEARC effect disappeared. In order to further explore the role of response mode, in Experiment 2, we changed the verbal response into arrow direction (named as visual coding condition). The outcome demonstrates that spatial STEARC effect occurred in spatial instruction condition, and visual STEARC effect occurred in visual instruction condition. The result demonstrates the spatial code associated with time is context dependent. In conclusion, the predominance of verbal coding occurs under verbal task instructions. However, in the spatial instruction condition, both verbal and spatial coding mechanisms could be activated to cause the spatial STEARC effect disappeared. In visual instruction condition, STEARC effect was activated to the same as in spatial response mode. Hence, these ?ndings clearly indicate that the cognitive origin of time–space associations is context dependent.

Key words: STEARC effect, verbal coding, visual coding, spatial coding

摘要： 时间和空间存在反应编码联合效应（spatial—temporal association of response codes effect, STEARC），该效应的编码是视觉空间性还是言语性还存在争议。本研究借鉴Georges（2015）的研究方式，以2秒内的时距为刺激，实验1采用言语反应和空间反应，词语和空间与时距的关系分为一致和不一致。结果发现言语反应时，短时距用“左边”反应快，长时距用“右边”反应快，空间反应时，时距和空间的一致性效应消失，表明言语编码参与两种反应形式的STEARC效应。实验2将词语改为箭头朝向（视觉编码条件），发现视觉编码和空间编码存在于相对应的反应形式中。研究表明时空关系的编码形式与具体任务要求有关。

关键词: STEARC效应, 言语编码, 视觉编码, 空间编码