In a dot-probe task, two cues-one emotional and one neutral-are followed by a probe in one of their locations. Faster responses to probes co-located with the emotional stimulus are taken as evidence of attentional bias. Several studies indicate that such attentional bias measures have poor reliability, even though ERP studies show that people reliably attend to the emotional stimulus. This inconsistency might arise because the emotional stimulus captures attention briefly (as indicated by ERP), but cues appear for long enough that attention can be redistributed before the probe onset, causing RT measures of bias to vary across trials. We tested this hypothesis by manipulating SOA (stimulus onset asynchrony between onset of the cues and onset of the probe) in a dot-probe task using angry and neutral faces. Across three experiments, the internal reliability of behavioural biases was significantly greater than zero when probes followed faces by 100 ms, but not when the SOA was 300, 500, or 900 ms. Thus, the initial capture of attention shows some level of consistency, but this diminishes quickly. Even at the shortest SOA internal reliability estimates were poor, and not sufficient to justify the use of the task as an index of individual differences in attentional bias.

Although many theories of attention highlight the importance of similarity between target and distractor items for selection, few studies have directly quantified the function underlying this relationship. Across two commonly used tasks—visual search and sustained attention—we investigated how target-distractor similarity impacts feature-based attentional selection. Importantly, we found comparable patterns of performance in both visual search and sustained feature-based attention tasks, with performance (response times and dʹ, respectively) plateauing at medium target-distractor distances (40°–50° around a luminance-matched color wheel). In contrast, visual search efficiency, as measured by search slopes, was affected by a much more narrow range of similarity levels (10°–20°). We assessed the relationship between target-distractor similarity and attentional performance using both a stimulus-based and psychologically-based measure of similarity and found this nonlinear relationship in both cases. However, psychological similarity accounted for some of the nonlinearities observed in the data, suggesting that measures of psychological similarity are more appropriate when studying effects of target-distractor similarities. These findings place novel constraints on models of selective attention and emphasize the importance of considering the similarity structure of the feature space over which attention operates. Broadly, the nonlinear effects of similarity on attention are consistent with accounts that propose attention exaggerates the distance between competing representations, possibly through enhancement of off-tuned neurons.

Conscious emotional processing is characterized by a coordinated set of responses across multiple physiological systems. Although emotional stimuli can evoke certain physiological responses even when they are suppressed from awareness, it is not known whether unconscious emotional responses comprise a similar constellation or are confined to specific systems. To compare physiological responses to emotional stimuli with and without awareness, we measured a range of responses while participants viewed positive, negative and neutral images that were accompanied by noise bursts to elicit startle reflexes. We measured four responses simultaneously – skin conductance and heart rate changes in response to the images themselves; and startle eye-blink and post-auricular reflexes in response to the noise bursts that occurred during image presentation. For half of the participants, the images were masked from awareness using continuous flash suppression. The aware group showed the expected pattern of response across physiological systems: emotional images (regardless of valence) evoked larger skin conductance responses (SCRs) and greater heart rate deceleration than neutral images, negative images enhanced eye-blink reflexes and positive images enhanced post-auricular reflexes. In contrast, we found a striking dissociation between measures for the unaware group: typical modulation of SCRs and post-auricular reflexes, but no modulation of heart rate deceleration or eye-blink reflexes. Our findings suggest that although some physiological systems respond to emotional stimuli presented outside of awareness, conscious emotional processing may be characterized by a broad and coordinated set of responses across systems.

Both visual attention and visual working memory tend to be studied either with very simple stimuli and low-level paradigms, which are designed to allow us to understand the representations and processes in detail; or with fully realistic stimuli that make such precise understanding difficult but are more representative of the real world. In this chapter we argue for an intermediate approach in which visual attention and visual working memory are studied by scaling up from the simplest settings to more complex settings that capture some aspects of the complexity of the real-world, while still remaining in the realm of well-controlled stimuli and wellunderstood tasks. We believe this approach, which we have been taking in our labs, will allow a generalizable set of knowledge about visual attention and visual working memory while maintaining the rigor and control that is typical of vision science and psychophysics studies.

Visual object recognition is impaired when stimuli are shown upside-down. This phenomenon is known as the inversion effect, and a substantial body of evidence suggests it is much larger for faces than non-face objects. The large inversion effect for faces has been widely used as key evidence that face processing is special, and hundreds of studies have used it as a tool to investigate face-specific processes. Here we show that large inversion effects are not specific to faces. We developed two car tasks that tap basic object recognition and within-class recognition. Both car tasks generated large inversion effects (~25% on a three-choice format), which were identical to those produced by parallel face tasks. Additional analyses showed that the large car inversion effects did not vary with expertise. Our findings demonstrate that non-face object recognition can depend on processes that are highly orientation-specific, challenging a critical behavioral marker of face-specific processes.