All in one fell Stroop: Examining consciousness thresholds with a multiple response paradigm.

Abstract

We test a novel multiple response paradigm for establishing objective and subjective thresholds of consciousness using the Stroop task. Replicating the threshold-defined qualitative differences originally reported by Cheesman and Merikle (1984, 1986), this paradigm also addresses trial-by-trial fluctuation in thresholds of objective and subjective thresholds. On each trial, suprathreshold was indicated by correct alternative-forced-choice (AFC) word identification and reporting word readability, subjective threshold by correct AFC and reporting no word readability, and objective threshold by incorrect AFC and reporting no word readability. As hypothesized, results showed Stroop effects at supra- and subjective thresholds, while eliminating the Stroop effect at objective threshold. A second experiment extended these results using a proportion congruent manipulation, whereby Stroop effects were larger with mostly congruent stimuli than mostly incongruent stimuli only at suprathreshold. This strategy effect was eliminated at subjective threshold, and Stroop effects were eliminated at objective threshold. Thus, the multiple response paradigm effectively and dynamically assesses cognitive processes at different thresholds of consciousness.

Classic Stroop Color Words Produce No Stroop Effect When the Display Characteristics Are Based Upon Emotional Stroop Studies With Subliminal Presentations

“…However, the shorter prime durations lack significant Stroop effects, which is in contrast to the results from emotional Stroop studies performed with subliminal stimuli. This overall pattern is, however, consistent with studies based upon traditional Stroop color words: Stroop effects are only obtained when participants can show some measurable behavioral sensitivity to the prime stimuli (Cheesman & Merikle, 1984, 1986; Kouider & Dupoux, 2004; Lorentz et al., 2015; Sand, 2016; Sand & Nilsson, 2017; Severance & Dyer, 1973; Tzelgov et al., 1997).…”

“…The null awareness criterion for the stimulus displays in these studies is often described as an objective threshold, such as identification d′ = 0 from a prime stimulus identification task. Most studies have found that no Stroop effect occurs when the display parameters are rigorously set to eliminate all behavioral evidence of sensitivity to the prime words (Cheesman & Merikle, 1984; Kouider & Dupoux, 2004; Lorentz et al., 2015; Severance & Dyer, 1973; Tzelgov, Porat, & Henik, 1997). However, a different finding emerges if the display parameters are relaxed slightly (e.g., longer durations, less masking) to make the prime word stimuli just slightly more visible to the participants.…”

“…However, a different finding emerges if the display parameters are relaxed slightly (e.g., longer durations, less masking) to make the prime word stimuli just slightly more visible to the participants. Word stimuli that are presented just above the objective threshold levels can produce Stroop effects even though the participants may deny that they consciously experienced the prime word stimuli (Cheesman & Merikle, 1986; Kouider & Dupoux, 2004; Lorentz et al., 2015; Sand, 2016; Sand & Nilsson, 2017; Van den Bussche et al., 2013). The size of the Stroop effect for these near threshold display conditions correlates with prime stimulus awareness: increasing prime stimulus awareness results in larger Stroop effects (Cheesman & Merikle, 1984; Kouider & Dupoux, 2004; Tzelgov et al., 1997).…”

“…For example, a prime word like “failure” is presented briefly in the color red for 20 milliseconds, followed immediately by a red target stimulus. A second display difference is that the studies using traditional Stroop stimuli often use backward pattern masks between the prime presentation and the colored target (e.g., Kouider & Dupoux, 2004; Lorentz et al., 2015). The emotional Stroop studies, in contrast, tend to use a brief stimulus presentation at the objective threshold (e.g., 20 milliseconds; participant sensitivity of approximately d′ = 0) that is immediately followed by the target stimulus (typically a nonword string of characters) that masks the prime word (e.g., MacLeod & Hagan, 1992).…”

Disentangling Genuine Semantic Stroop Effects in Reading from Contingency Effects: On the Need for Two Neutral Baselines

“…A possible explanation for why Experiment 2 did not demonstrate the same interference may involve inclusion of a congruent condition, although this appears unlikely. Specifically, the inclusion of congruent stimuli, and greater proportions of congruent stimuli relative to incongruent stimuli, generally increase the overall size of the Stroop effect (Cheesman and Merikle, 1986 ; Lorentz et al, 2015 ).…”