Clarifying the effect of facial emotional expression on inattentional blindness

https://doi.org/10.1016/j.concog.2022.103304Get rights and content

Highlights

  • The semantic value of a stimulus partly influences its conscious detection.

  • The semantic value of a stimulus strongly influences its conscious identification.

  • Different contexts might cause the mixed results in inattentional blindness research.

Abstract

Conscious perception often fails when an object appears unexpectedly and our attention is focused elsewhere (inattentional blindness). While various factors have been identified that modulate the likelihood of this failure of awareness, the semantic value of facial emotional expression of the unexpected stimulus is not clear. A total of 457 participants performed a static or a dynamic inattentional blindness paradigm with one of three face icons as the unexpected stimulus. Whereas we only found an effect of frowning faceś semantic value on its conscious detection in the static paradigm, we found in both paradigms a substantial effect of frowning as well as happy faceś semantic value on their conscious identification. Thus, we assume that the semantic value of unexpected stimuli, based on facial emotional expressions, controls attentional prioritization and influences inattentional blindness. Furthermore, we argue that every finding in inattentional blindness research should be considered in its respective context.

Introduction

Our environment is complex and rich in detail while our perceptual and cognitive resources are strictly limited (Fecteau & Munoz, 2006). Consequently, only a small part of the available sensory input is analyzed at a given time (Bundesen, 1990, Desimone and Duncan, 1995). Although human perception has evolved into a potent and efficient system, we still fall prey to astonishing failures of awareness. One striking example is the phenomenon that we often fail to notice an unexpected object in our direct view when our attention is occupied (inattentional blindness; Mack and Rock, 1998, Simons and Chabris, 1999).

While the likelihood that an unexpected object is noticed has been investigated extensively in the context of individual differences (Bredemeier et al., 2014, Kreitz et al., 2015, Memmert, 2006, Memmert, 2014) and situational factors (Kreitz et al., 2016, Most et al., 2001), the semantic value of the unexpected object has received relatively little research attention. This is surprising as semantic value has been suggested as the main determinant of whether the unexpected object succeeds in capturing attention under conditions of inattention (Mack & Rock, 1998).

Semantic value is here seen as an umbrella-term, covering the strength of a stimuluś personal, social, or evolutionary meaning which leads to an attentional bias that involuntarily drives attentional selection in favour of meaningful stimuli. Semantic value based on the personal meaning of monetary reward, learned incidentally over a short period of time (Redlich, Schnuerch, Memmert, & Kreitz, 2019), or the personal meaning of stimuli characteristics related to gains or losses in custom video games (Stothart, Wright, Simons & Boot, 2017) does not seem to affect the likelihood of failure of awareness. Furthermore, semantic value based on a stimuluś personal meaning can be quite complex and, naturally, change over time with circumstances and needs: In one study, ice-cream stimuli were only more likely to be noticed by female participants and only by those who experienced strong ice-cream cravings (Li et al., 2015).

Whereas semantic value based on personal meaning seems to be very complex and flexible, one might assume a more stable semantic value when it is based on the evolutionary meaning of a stimulus. Previous studies have shown that semantic value based on the predetermined evolutionary meaning of threat (New & German, 2015) and semantic value based on personal overlearned meaning for onés name (Mack & Rock, 1998) indeed affect the susceptibility to inattentional blindness. Furthermore, the evolutionary predetermined semantic value based on facial emotional expression has been investigated in several studies and seems to increase noticing rates of unexpected objects. Indeed, several studies are in favor of this view: In their book “Inattentional Blindness” Mack and Rock (1998) reported that cartoon-like happy faces were more likely to be noticed compared to other stimuli such as circles and argued that this effect is driven by the stimuli’s importance (Mack, Pappas, Silverman, & Gay, 2002). Over a decade later, Devue, Laloyaux, Feyers, Theeuwes, and Brédart (2009) found a similar effect of higher detection rates for upright pictures of faces compared to objects or inverted faces. Since upright and inverted faces shared similar low-level physical characteristics, the difference in detection rates should be solely caused by the stimulus value. Similarly, Lee and Telch (2008) found higher detection rates for smiling cartoon faces compared to circles.

However, on a closer look, findings regarding this type of semantic value are not straightforward in the context of inattentional blindness research: Mack and Clarke (2012) were not able to support the assumption that the presence of faces in a party scene could alone account for the higher detection rate of this scene in an inattentional blindness paradigm. Similarly, and in contrast to cartoon-like happy faces, Mack and Rock (1998) found that cartoon-like sad faces were not more likely to be noticed under conditions of inattention than circles. Also, effects of the semantic value based on facial emotional expression on inattentional blindness have mainly been observed for faces compared to stimuli with different low-level physical characteristics such as circles or other objects (Devue et al., 2009, Lee and Telch, 2008). When comparing happy faces as well as sad faces with scrambled faces, to ensure that all stimuli had common low-level physical characteristics, no significant differences were found (Mack & Rock, 1998). Similarly, the results by Lee & Telch (2008) did not support significant differences between frowning cartoon faces and scrambled cartoon faces. This leads to the assumption that differences in low-level physical characteristics were responsible for the different noticing rates of unexpected stimuli, rather than the semantic value of faces in general or their facial emotional expressions.

One might assume that, based on their semantic value, faces are not only more likely to be detected, but also more likely to be recognized. However, Devue et al. (2009) showed that the recognition rate did not significantly differ between faces and objects.

Furthermore, several studies showed effects of facial emotional expression on inattentional blindness only in combination with additional types of semantic value based on personal meaning such as social anxiety (Lee & Telch, 2008) or mood congruency (Becker & Leinenger, 2011); only those faces were detected with a higher probability whose displayed emotion was congruent with the participants’ mood and only if their mood was sadness.

One might contemplate different reasons for such ambiguous findings:.

(A) The difference between studies might be related to the used paradigm: Whereas studies supporting the effect of semantic value based on facial emotional expression on inattentional blindness used the static paradigm by Mack and Rock (1998) (e.g. Devue et al., 2009) other studies with less supportive findings used other paradigms such as the dynamic IB-task by Most et al. (2001) (e.g., Becker & Leinenger, 2011).

(B) Potentially, the effect of semantic value based on facial emotional expression on inattentional blindness might also be trapped by publication bias as many other phenomena in the past decades (Francis, 2012). Such a publication bias could suggest that an incidental effect is true or could overestimate the size of true effects.

(C) It might be that several studies are underpowered; some of the previous studies report and discuss non-significant findings but present medium to large effects. An increase in power for future studies could counteract this phenomenon and provide more reliable findings even for smaller effects of semantic value.

In the present study, we aimed to circumvent the three potential flaws of previous research: We replicated the effect of semantic value based on facial emotional expression on inattentional blindness in a big sample to increase the power of our study and publish it independent of results (publication bias). This replication includes two experiments using two types of the inattentional blindness paradigm (static and dynamic) to increase the generalizability of our findings. In both experiments we used face icons (happy, frowning, & scrambled faces) to minimize the low-level physical differences to a substantial degree.

Our study was designed to clarify if semantic value based on facial emotional expression modifies the detection rate of unexpected stimuli under conditions of inattention. If this were the case, we might support the role of a stimulus' meaning as an additional factor (next to physical properties for example) that controls attentional prioritization. Such clarification would offer new arguments for the ongoing debate about the effect of facial emotional expression on inattentional blindness and, about the effect of semantic value on this failure of awareness. This would increase our understanding of the factors modulating susceptibility to inattentional blindness in daily life as well as make it easier for future research to take semantic value into account and control for it.

Section snippets

Participants

A statistical power analysis was performed to estimate the necessary sample size (G*Power 3.1.9.2, Germany). As previous studies reported medium to large effect-sizes (Becker & Leinenger, 2011; Lee & Telch, 2008; Mack & Rock, 1998), we aimed to detect effects of at least medium size (w = 0.3). To perform four chi-square tests in total we ensured sufficient power of 0.95 for each individual test by using a power of 0.99 for our overall power analysis. With a power = 0.99 and an alpha = 0.05 the

Experiment 2

To increase the generalizability of our results we aimed to replicate our results of Experiment 1 with a dynamic inattentional blindness task (Most et al., 2001).

Discussion

In two large-scale studies, we investigated the effect of semantic facial expressions on inattentional blindness. All analyses were conducted as preregistered and can be found in the results-section or the supplemental material. Our findings only partly support the notion that the semantic facial expression of an unexpected stimulus affects the likelihood that it is noticed under conditions of inattention. Faces were more likely to be noticed under conditions of inattention than scrambled faces

Conclusion and future prospects

The present findings suggest that the probability to detect unexpected stimuli is only partly influenced by their semantic value based on facial emotional expressions; only frowning faces were detected more readily in a static inattentional blindness paradigm. However, the present findings provide substantial evidence that the probability to identify unexpected stimuli is strongly influenced by their semantic value based on facial emotional expressions independent of the expressions valence.

CRediT authorship contribution statement

Dennis Redlich: Conceptualization, Methodology, Software, Writing – original draft, Writing – review & editing. Daniel Memmert: Resources, Supervision. Carina Kreitz: Conceptualization, Methodology, Writing – original draft, Writing – review & editing.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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