It was hypothesized that self-rated language proficiency would relate to performance on the Stroop tasks. This hypothesis was not fully confirmed for any of the groups for either language, but several interesting findings related to language proficiency were found.
Rather than a Stroop effect, the two hearing groups demonstrated a reverse Stroop on the ASL tasks. That is, the hearing participants were faster on the incongruent than the control conditions for the color and shape words. However, the magnitude of this reverse Stroop may have been moderated by ASL proficiency. Every additional point that a hearing participant assigned on the LEAP-Q for ASL comprehension resulted in a more positive reverse Stroop effect. However, when divided into their respective groups, the HP and HNP groups diverged somewhat. The HP participants were expected to produce a Stroop effect on the ASL tasks because of their signing skill level but instead showed a reduced reverse Stroop magnitude (i.e., 65 ms for color, 52 ms for shape) compared to the HNP group. This reduction in their reverse Stroop effect might have reflected their reduced signing proficiency.
The DP group’s relationship between their self-rated English proficiency and
performance on the CRTT-R-WF also was complex. For each additional point assigned on the LEAP-Q, the DP participants were 88 ms faster on the color word and 96 ms faster on the shape word across both control and incongruent tasks, indicating that the more proficient DP
participants were with English, the faster they responded overall. This finding suggested that the more proficient DP participants were faster readers or processors of language, and thus faster responders than the less proficient Deaf participants regardless of condition. Consistent with this argument was the observation that the more proficient DP participants spent less time on the shape word in the CRTT-R-WF than the less proficient DP participants. Participants comprising the DP group demonstrated interference, evidenced by prolonged processing time on the
incongruent condition; however, the average processing times across both control and
incongruent conditions of those DP individuals who rated themselves as being more proficient were smaller. This was consistent with the interpretation that the more proficient readers within the DP group were faster at inhibiting the colored font in the incongruent condition for the CRTT-R-WF-STROOP task.
It was reasonable to expect that proficient language users would demonstrate longer reading times on incongruent stimuli due to the required inhibition; however, what is known about the bilingual advantage is that individuals who are more proficient in two languages show reduced interference due to more automatic cognitive control. It does not appear that the DP group demonstrated a bilingual advantage because the magnitude of interference was not
correlated with participant’s self-rated language proficiency although it may have been evident in some of the Deaf participants.
When the DP group’s LEAP-Q self-ratings on ASL comprehension were compared to the Stroop effect on the CRTT-ASL, the LEAP-Q values did not predict a Stroop effect on the color or shape words on the CRTT-ASL. Although the LEAP-Q scores accounted for a substantive amount of the variance within the DP group the scores did not predict Stroop effects in ASL. Similar to English, the ASL results showed that the higher a Deaf participant rated their comprehension of ASL, the faster their reading times for the color word for control and incongruent sentence level ASL tasks. This is an example of a potential language processing advantage for the more proficient DP participants. Self-rated ASL proficiency was added to the model for processing time on the shape word, to investigate how ASL proficiency related to Stroop results. The results indicated that the difference between incongruent and control conditions for ASL signers who reported being more proficient (demonstrated by larger self- rating scores on the LEAP-Q) in ASL was smaller than for ASL signers who reported being less proficient in ASL. Those who were proficient were able to identify the shape more
automatically, recovering from the interference experienced on the color word more quickly. The relationship between self-rated LEAP-Q ASL comprehension scores and the Stroop effect in reading written English also was investigated because of the interdependent relationship that ASL and English have on language development for many Deaf individuals. For example, it is believed that some Deaf individuals recode written English via ASL. Therefore, the ASL LEAP-Q comprehension scores were added to the English reading Stroop model, which eliminated the Stroop effect for the English reading tasks. Self-rated ASL comprehension LEAP-Q scores accounted for a substantive amount of variance in the model. What also is interesting is that with each additional point on the LEAP-Q in ASL resulted in faster reading times on English color words by 109 ms and shape words by 116 ms. This means that the Deaf
participants who were more skilled at comprehending ASL also processed written English faster, possibly due to being natively better language users and bringing these attributes to both
language tasks. This finding also suggested a relationship between ASL skills and processing of written English. In thinking about the variety of language experiences reported by the DP group members, many of these individuals experienced linguistic deprivation at critical language learning ages; however, despite potential for language deprivation, the majority of the DP group members experienced interference in their second language. This makes sense, as ASL is often the dominant language used by Deaf ASL users, and is often used to scaffold literacy
development. These findings highlight the importance of language proficiency and the role it plays in general language processing. Perhaps frequent language experiences and exposure provided strong language models, impact language processing and subsequent performance on cognitive-linguistic tasks such as the Stroop effect.