Gernot Horstmann

Search asymmetries with real faces : Testing the anger-superiority effect

The anger-superiority hypothesis states that angry faces are detected more efficiently than friendly faces. Previously research used schematized stimuli, which minimizes perceptual confounds, but violates ecological validity. The authors argue that a confounding of appearance and meaning is unavoidable and even unproblematic if real faces are presented. Four experiments tested carefully controlled photos in a search-asymmetry design. Experiments 1 and 2 revealed more efficient detection of an angry face among happy faces than vice versa. Experiment 3 indicated that the advantage was due to the mouth, but not to the eyes, and Experiment 4, using upright and inverted thatcherized faces, suggests a perceptual basis. The results are in line with a sensory-bias hypothesis that facial expressions evolved to exploit extant capabilities of the visual system.

What do facial expressions convey : Feeling states, behavioral intentions, or action requests?

Emotion theorists assume certain facial displays to convey information about the expressers emotional state. In contrast, behavioral ecologists assume them to indicate behavioral intentions or action requests. To test these contrasting positions, over 2,000 online participants were presented with facial expressions and asked what they revealed-feeling states, behavioral intentions, or action requests. The majority of the observers chose feeling states as the message of facial expressions of disgust, fear, sadness, happiness, and surprise, supporting the emotions view. Only the anger display tended to elicit more choices of behavioral intention or action request, partially supporting the behavioral ecology view. The results support the view that facial expressions communicate emotions, with emotions being multicomponential phenomena that comprise feelings, intentions, and wishes.

Evidence for Attentional Capture by a Surprising Color Singleton in Visual Search

Three experiments were conducted to investigate whether surprising color singletons capture attention. Participants performed a visual search task in which a target letter had to be detected among distractor letters. Experiments 1 and 2 assessed accuracy as the dependent variable. In Experiment 1, the unannounced presentation of a color singleton 500 ms prior to the letters (and in the same position as the target letter) resulted in better performance than in the preceding conjunction search segment, in which no singleton was presented, and performance was as good in this surprise-singleton trial as in the following feature search segment, in which the singleton always coincided with the target. In contrast, no improvement was observed when the color singleton was presented simultaneously with the letters in Experiment 2, indicating that attentional capture occurred later in the surprise trial than in the feature search segment. In Experiment 3, set size was varied, and reaction time was the dependent variable. Reaction time depended on set size in the conjunction search segment, but not in the surprise trial nor in the feature search segment. The results of the three experiments support the view that surprising color singletons capture attention independently of a corresponding attentional set.

Coherence between Emotion and Facial Expression: Evidence from Laboratory Experiments:

Evidence on the coherence between emotion and facial expression in adults from laboratory experiments is reviewed. High coherence has been found in several studies between amusement and smiling; low to moderate coherence between other positive emotions and smiling. The available evidence for surprise and disgust suggests that these emotions are accompanied by their “traditional” facial expressions, and even components of these expressions, only in a minority of cases. Evidence concerning sadness, anger, and fear is very limited. For sadness, one study suggests that high emotion–expression coherence may exist in specific situations, whereas for anger and fear, the evidence points to low coherence. Insufficient emotion intensity and inhibition of facial expressions seem unable to account for the observed dissociations between emotion and facial expression.

Preattentive face processing: What do visual search experiments with schematic faces tell us?

In recent research, several experiments have tested a preattentive threat-advantage hypothesis that threatening or negative faces can be discriminated preattentively, by using the visual search paradigm. However, supporting evidence is nonuniform, giving rise to the suspicion that stimulus factors rather than the stimulis category of facial threat versus friendliness are responsible for sporadic demonstrations of a threat advantage. However, it is also possible that differences in experimental procedure contribute to the heterogeneous results. To test this possibility I selected examples from the past literature and presented them within the same constant experimental setting. I found a consistent advantage for negative face targets among positive face distractors with all stimulus pairs. Search slopes, however, mostly revealed inefficient search, questioning the preattentive discrimination of facial affect.

Flanker effects with faces may depend on perceptual as well as emotional differences.

Do threatening or negative faces capture attention? The authors argue that evidence from visual search, spatial cuing, and flanker tasks is equivocal and that perceptual differences may account for effects attributed to emotional categories. Empirically, the authors examine the flanker task. Although they replicate previous results in which a positive face flanked by negative faces suffers more interference than a negative face flanked by positive faces, further results indicate that face perception is not necessary for the flanker-effect asymmetry and that the asymmetry also occurs with nonemotional stimuli. The authors conclude that the flanker-effect asymmetry with affective faces cannot be unambiguously attributed to emotional differences and may well be due to purely perceptual differences between the stimuli.

Attentional Capture by an Unannounced Color Singleton Depends on Expectation Discrepancy

Eight experiments examined the conditions under which a color singleton that is presented for the 1st time without prior announcement captures attention. The main hypothesis is that an unannounced singleton captures attention to the extent that it deviates from expectations. This hypothesis was tested within a visual-search paradigm in which set-size effects were used to infer attentional capture. The results showed that attentional capture by an unannounced color singleton was due to a mismatch with expectations concerning the color of the object and not due to its being a singleton. Thus, the results imply that theories of attention have to consider expectation discrepancy as a determinant of attention shifts.

Preemptive control of attentional capture by colour: Evidence from trial-by-trial analyses and orderings of onsets of capture effects in reaction time distributions

According to the preemptive-control hypothesis, participants can specify their control settings to attend to relevant target colours or to ignore the irrelevant distractor colours in advance of the displays. Two predictions of this hypothesis were tested. First, with the control settings being specified in advance, capture by a stimulus that better matches the settings was expected to temporally precede capture by a stimulus that matches the setting less well. Second, with the control settings being specified in advance, stronger capture by the better matching than by the less matching stimulus was predicted not to be a stimulus-driven consequence of the target colour in a preceding trial. Both predictions were shown to hold true under different conditions in three experiments.

Social facilitation with social robots

Regarding the future usage of social robots in workplace scenarios, we addressed the question of potential mere robotic presence effects on human performance. Applying the experimental social facilitation paradigm in social robotics, we compared task performance of 106 participants on easy and complex cognitive and motoric tasks across three presence groups (alone vs. human present vs. robot present). Results revealed significant evidence for the predicted social facilitation effects for both human and robotic presence compared to an alone condition. Implications of these findings are discussed with regard to the consideration of the interaction of robotic presence and task difficulty in modeling robotic assistance systems.

More efficient rejection of happy than of angry face distractors in visual search.

In the present study, we examined whether the detection advantage for negative-face targets in crowds of positive-face distractors over positive-face targets in crowds of negative faces can be explained by differentially efficient distractor rejection. Search Condition A demonstrated more efficient distractor rejection with negative-face targets in positive-face crowds than vice versa. Search Condition B showed that target identity alone is not sufficient to account for this effect, because there was no difference in processing efficiency for positive- and negative-face targets within neutral crowds. Search Condition C showed differentially efficient processing with neutral-face targets among positive- or negative-face distractors. These results were obtained with both a within-participants (Experiment 1) and a between-participants (Experiment 2) design. The pattern of results is consistent with the assumption that efficient rejection of positive (more homogenous) distractors is an important determinant of performance in search among (face) distractors.