Abstract
It has been suggested that the interference in the Stroop task arises due to both information conflict (color vs. word meaning) and task conflict (respond to the color vs. read the word). Interestingly, the task conflict (faster responses in the congruent condition compared to the neutral condition) is influenced by the readability of the stimulus. However, behavioral results indicate the influence of the contribution of readability to the task conflict appears only when vocal responses are required. We conducted a Stroop experiment with four readability levels of neutrals. Participants were required to respond manually, and both their response times and pupil dilation were measured. Our results showed the slowest responses for incongruent trials and the fastest responses for congruent trials. However, no differences in responses were found between the readability levels of the neutrals. In contrast, pupil dilation showed the largest dilation in the incongruent trials and smallest dilation in the neutral trials. In addition, the differences between congruent and neutral trials were influenced by the readability of the stimulus. Specifically, unreadable neutral stimuli showed meaningful differences early on, which also remained for longer time compared with readable neutral stimuli. These results are important and can help in specifying new requirements regarding the theory and modeling of the Stroop task; in particular, studies that want to control the neutrality of their neutral trials should take the readability into account.
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References
Augustinova, M., & Ferrand, L. (2012). The influence of mere social presence on Stroop interference: New evidence from the semantically-based Stroop task. Journal of Experimental Social Psychology, 48(5), 1213–1216. https://doi.org/10.1016/J.JESP.2012.04.014.
Augustinova, M., & Ferrand, L. (2014). Automaticity of word reading: Evidence from the semantic Stroop paradigm. Current Directions in Psychological Science, 23(5), 343–348. https://doi.org/10.1177/0963721414540169.
Augustinova, M., Silvert, L., Spatola, N., & Ferrand, L. (2018). Further investigation of distinct components of Stroop interference and of their reduction by short response-stimulus intervals. Acta Psychologica, 189, 54–62. https://doi.org/10.1016/j.actpsy.2017.03.009.
Bench, C. J., Frith, C. D., Grasby, P. M., Friston, K. J., Paulesu, E., Frackowiak, R. S. J., et al. (1993). Investigations of the functional anatomy of attention using the Stroop test. Neuropsychologia, 31(9), 907–922. https://doi.org/10.1016/0028-3932(93)90147-R.
Brown, G. G., Kindermann, S. S., Siegle, G. J., Granholm, E., Wong, E. C., & Buxton, R. B. (1999). Brain activation and pupil response during covert performance of the Stroop Color Word task. Journal of the International Neuropsychological Society, 5(4), 308–319.
Brown, T. L. (2011). The relationship between Stroop interference and facilitation effects: Statistical artifacts, baselines, and a reassessment. Journal of Experimental Psychology: Human Perception and Performance, 37(1), 85–99. https://doi.org/10.1037/a0019252.
Bush, G., Luu, P., & Posner, M. I. (2000). Cognitive and emotional influences in anterior cingulate cortex. Trends in Cognitive Sciences, 4(6), 215–222. https://doi.org/10.1016/S1364-6613(00)01483-2.
Carter, C. S., Mintun, M., & Cohen, J. D. (1995). Interference and facilitation effects during selective attention: An H215O PET study of Stroop task performance. NeuroImage, 2(4), 264–272. https://doi.org/10.1006/NIMG.1995.1034.
Entel, O., Tzelgov, J., Bereby-Meyer, Y., & Shahar, N. (2015). Exploring relations between task conflict and informational conflict in the Stroop task. Psychological Research Psychologische Forschung, 79(6), 913–927. https://doi.org/10.1007/s00426-014-0630-0.
Fox, L. A., Shor, R. E., & Steinman, R. J. (1971). Semantic gradients and interference in naming color, spatial direction, and numerosity. Journal of Experimental Psychology, 91(1), 59–65. https://doi.org/10.1037/h0031850.
Goldfarb, L., & Henik, A. (2007). Evidence for task conflict in the Stroop effect. Journal of Experimental Psychology: Human Perception and Performance, 33(5), 1170–1176. https://doi.org/10.1037/0096-1523.33.5.1170.
Henik, A., Bugg, J. M., & Goldfarb, L. (2018). Inspired by the past and looking to the future of the Stroop effect. Acta Psychologica, 189, 1–3. https://doi.org/10.1016/j.actpsy.2018.06.007.
Hershman, R., Gozansky, E., Keha, E., Kalanthroff, A., & Henik, A. (2020). Pupillometric comparison between vocal and manual color-word Stroop tasks. Manuscript in preparation.
Hershman, R., & Henik, A. (2019). Dissociation between reaction time and pupil dilation in the Stroop task. Journal of Experimental Psychology. Learning, Memory, and Cognition.. https://doi.org/10.1037/xlm0000690.
Hershman, R., & Henik, A. (2020). Pupillometric contributions to deciphering Stroop conflicts. Memory & Cognition. https://doi.org/10.3758/s13421-019-00971-z.
Hershman, R., Henik, A., & Cohen, N. (2018). A novel blink detection method based on pupillometry noise. Behavior Research Methods, 50(1), 107–114. https://doi.org/10.3758/s13428-017-1008-1.
Hershman, R., Henik, A., & Cohen, N. (2019). CHAP: Open-source software for processing and analyzing pupillometry data. Behavior Research Methods, 51(3), 1059–1074. https://doi.org/10.3758/s13428-018-01190-1.
Kahneman, D., & Beatty, J. (1966). Pupil diameter and load on memory. Science, 154(3756), 1583–1585. https://doi.org/10.1126/science.154.3756.1583.
Kalanthroff, E., Davelaar, E. J., Henik, A., Goldfarb, L., & Usher, M. (2018). Task conflict and proactive control: A computational theory of the Stroop task. Psychological Review, 125(1), 59–82. https://doi.org/10.1037/rev0000083.
Kalanthroff, E., Goldfarb, L., & Henik, A. (2013). Evidence for interaction between the stop signal and the Stroop task conflict. Journal of Experimental Psychology: Human Perception and Performance, 39(2), 579–592. https://doi.org/10.1037/a0027429.
Kalanthroff, E., & Henik, A. (2013). Individual but not fragile: Individual differences in task control predict Stroop facilitation. Consciousness and Cognition, 22(2), 413–419. https://doi.org/10.1016/J.CONCOG.2013.01.010.
Kalanthroff, E., & Henik, A. (2014). Preparation time modulates pro-active control and enhances task conflict in task switching. Psychological Research Psychologische Forschung, 78(2), 276–288. https://doi.org/10.1007/s00426-013-0495-7.
Kinoshita, S., De Wit, B., & Norris, D. (2017). The magic of words reconsidered: Investigating the automaticity of reading color-neutral words in the Stroop task. Journal of Experimental Psychology: Learning, Memory, and Cognition, 43(3), 369–384. https://doi.org/10.1037/xlm0000311.
Kinoshita, S., Mills, L., & Norris, D. (2018). The semantic Stroop effect is controlled by endogenous attention. Journal of Experimental Psychology: Learning, Memory, and Cognition, 44(11), 1730–1742. https://doi.org/10.1037/xlm0000552.
Klein, G. S. (1964). Semantic power measured through the interference of words with color-naming. The American Journal of Psychology, 77(4), 576–588. https://doi.org/10.2307/1420768.
Laeng, B., Ørbo, M., Holmlund, T., & Miozzo, M. (2011). Pupillary Stroop effects. Cognitive Processing, 12(1), 13–21. https://doi.org/10.1007/s10339-010-0370-z.
Levin, Y., & Tzelgov, J. (2014). Conflict components of the Stroop effect and their "control". Frontiers in Psychology, 5, 463. https://doi.org/10.3389/fpsyg.2014.00463.
Levin, Y., & Tzelgov, J. (2016). Contingency learning is not affected by conflict experience: Evidence from a task conflict-free, item-specific Stroop paradigm. Acta Psychologica, 164, 39–45. https://doi.org/10.1016/J.ACTPSY.2015.12.009.
Levin, Y., & Tzelgov, J. (2016). What Klein’s “semantic gradient” does and does not really show: Decomposing Stroop interference into task and informational conflict components. Frontiers in Psychology, 7, 249. https://doi.org/10.3389/fpsyg.2016.00249.
MacLeod, C. M. (1991). Half a century of research on the Stroop effect: An integrative review. Psychological Bulletin, 109(2), 163–203. https://doi.org/10.1037/0033-2909.109.2.163.
MacLeod, C. M., & MacDonald, P. A. (2000). Interdimensional interference in the Stroop effect: Uncovering the cognitive and neural anatomy of attention. Trends in Cognitive Sciences, 4(10), 383–391. https://doi.org/10.1016/S1364-6613(00)01530-8.
Monsell, S., Taylor, T. J., & Murphy, K. (2001). Naming the color of a word: Is it responses or task sets that compete? Memory & Cognition, 29(1), 137–151. https://doi.org/10.3758/BF03195748.
Rogers, R. D., & Monsell, S. (1995). Costs of a predictible switch between simple cognitive tasks. Journal of Experimental Psychology: General, 124(2), 207–231. https://doi.org/10.1037/0096-3445.124.2.207.
Sharma, D., & McKenna, F. P. (1998). Differential components of the manual and vocal Stroop tasks. Memory & Cognition, 26(5), 1033–1040. https://doi.org/10.3758/BF03201181.
Siegle, G. J., Ichikawa, N., & Steinhauer, S. (2008). Blink before and after you think: Blinks occur prior to and following cognitive load indexed by pupillary responses. Psychophysiology, 45(5), 679–687. https://doi.org/10.1111/j.1469-8986.2008.00681.x.
Siegle, G. J., Steinhauer, S. R., & Thase, M. E. (2004). Pupillary assessment and computational modeling of the Stroop task in depression. International Journal of Psychophysiology, 52(1), 63–76. https://doi.org/10.1016/J.IJPSYCHO.2003.12.010.
Stroop, J. R. (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18(6), 643–662. https://doi.org/10.1037/h0054651.
van der Wel, P., & van Steenbergen, H. (2018). Pupil dilation as an index of effort in cognitive control tasks: A review. Psychonomic Bulletin & Review, 25(6), 2005–2015. https://doi.org/10.3758/s13423-018-1432-y.
Waszak, F., Hommel, B., & Allport, A. (2003). Task-switching and long-term priming: Role of episodic stimulus–task bindings in task-shift costs. Cognitive Psychology, 46(4), 361–413. https://doi.org/10.1016/S0010-0285(02)00520-0.
Acknowledgements
We wish to thank Ms. Desiree Meloul for helpful comments and useful input on this article. In addition, we wish to thank our research assistants—Einav Gozansky and Bar Sofer—for their help with the running of the experiment. This research was supported by Grant 146/16 from the Israeli Science Foundation.
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Hershman, R., Levin, Y., Tzelgov, J. et al. Neutral stimuli and pupillometric task conflict. Psychological Research 85, 1084–1092 (2021). https://doi.org/10.1007/s00426-020-01311-6
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DOI: https://doi.org/10.1007/s00426-020-01311-6