We analyzed the effects of bilingualism and age on executive function. We examined these variables along a continuum, as opposed to dichotomizing them. We investigated the impact that bilingualism and age have on two measures of executive control (Stroop and Flanker). The mouse-tracking paradigm allowed us to examine the continuous dynamics of the responses as participants completed each trial. First, we found that the Stroop effect was reduced with younger age and higher levels of bilingualism; however, no Bilingualism by Age interaction emerged. Second, after controlling for baseline, the Flanker effect was not influenced by bilingualism or age. These results support the notion that bilingualism is one way of enhancing some aspects of executive function - specifically those related to the Stroop task - across the adult life span. In sum, different levels of bilingualism, and different ages, result in varying degrees of executive function as measured by the Stroop task.

We used mouse tracking to compare the performance of bilinguals and monolinguals in a Stroop task. Participants were instructed to respond to the color of the words (e.g., blue in yellow font) by clicking on response options on the screen. We recorded participants’ movements of a computer mouse: when participants started moving (initiation times), and how fast they moved towards the correct response (x-coordinates over time). Interestingly, initiation times were longer for bilinguals than monolinguals. Nevertheless, when comparing mouse trajectories, bilinguals moved faster towards the correct response. Taken together, these results indicate that bilinguals behave qualitatively differently from monolinguals; bilinguals are “experts” at managing conflicting information. Experts across many different domains take longer to initiate a response, but then they outperform novices. These qualitative differences in performance could be at the root of apparently contradictory findings in the bilingual literature.

Purpose: Recent research has provided support for linguistic coactivation, the view that the two languages of a bilingual are simultaneously active. Importantly, even if the system is fundamentally nonselective, the two languages of a bilingual can be activated to different degrees. The main contribution of the present paper is to empirically test what "different degrees of activation" really means. Differences could emerge in the timing or the magnitude of language activation. Methodology: Most of the research to date has been based on experiments using reaction times. In the present experiment participants responded to a bilingual Stroop task using a computer mouse. We argue that mouse tracking can provide new insights into the temporal dynamics of cognitive processes. Data and analysis: We used a series of t-tests to analyze participants' mouse trajectories (n = 20). We compared the x-coordinates over time for each of the four experimental conditions (Congruent-Within, Congruent-Between, Incongruent-Within, Incongruent-Between) with the x-coordinates over time for the control trajectory. Findings: Differences in the timing, but not the magnitude, of interference are at the root of the differential effects within and between languages. Within-language interference emerged 80 ms earlier than between-language interference. Originality: To our knowledge, the current experiment is the first to use the dynamic mouse-tracking paradigm to compare the time course of the two languages of a bilingual participant. Implications: The mouse-tracking paradigm can help to distinguish between the timing and the magnitude of interference, informing current theories of the bilingual mind.

In a reverse Stroop task, observers respond to the meaning of a color word irrespective of the color in which the word is printed—for example, the word red may be printed in the congruent color (red), an incongruent color (e.g., blue), or a neutral color (e.g., white). Although reading of color words in this task is often thought to be neither facilitated by congruent print colors nor interfered with incongruent print colors, this interference has been detected by using a response method that does not give any bias in favor of processing of word meanings or processing of print colors. On the other hand, evidence for the presence of facilitation in this task has been scarce, even though this facilitation is theoretically possible. By modifying the task such that participants respond to a stimulus color word by pointing to a corresponding response word on a computer screen with a mouse, the present study investigated the possibility that not only interference but also facilitation would take place in a reverse Stroop task. Importantly, in this study, participants’ responses were dynamically tracked by recording the entire trajectories of the mouse. Arguably, this method provided richer information about participants’ performance than traditional measures such as reaction time and accuracy, allowing for more detailed (and thus potentially more sensitive) investigation of facilitation and interference in the reverse Stroop task. These trajectories showed that the mouse’s approach toward correct response words was significantly delayed by incongruent print colors but not affected by congruent print colors, demonstrating that only interference, not facilitation, was present in the current task. Implications of these findings are discussed within a theoretical framework in which the strength of association between a task and its response method plays a critical role in determining how word meanings and print colors interact in reverse Stroop tasks.