Jelena Ristic

Are eyes special? It depends on how you look at it

Recent behavioral data have shown that central nonpredictive gaze direction triggers reflexive shifts of attention toward the gazed-at location (e.g., Friesen & Kingstone, 1998). Friesen and Kingstone suggested that this reflexive orienting effect is unique to biologically relevant stimuli. Three experiments were conducted to test this proposal by comparing the attentional orienting produced by nonpredictive gaze cues (biologically relevant) with the attentional orienting produced by nonpredictive arrow cues (biologically irrelevant). Both types of cues produced reflexive orienting in adults (Experiment 1) and preschoolers (Experiment 2), suggesting that gaze cues are not special. However, Experiment 3 showed that nonpredictive arrows produced reflexive orienting in both hemispheres of a split-brain patient. This contrasts with Kingstone, Friesen, and Gazzanigas (2000) finding that nonpredictive gaze cues produce reflexive orienting only in the face-processing hemisphere of split-brain patients. Therefore, although nonpredictive eyes and arrows may produce similar behavioral effects, they are not subserved by the same brain systems. Together, these data provide important insight into the nature of the representations of directional stimuli involved in reflexive attentional orienting.

Attentional effects of counterpredictive gaze and arrow cues.

The authors used counterpredictive cues to examine reflexive and volitional orienting to eyes and arrows. Experiment 1 investigated the effects of eyes with a novel design that allowed for a comparison of gazed-at (cued) target locations and likely (predicted) target locations against baseline locations that were not cued and not predicted. Attention shifted reflexively to the cued location and volitionally to the predicted location, and these 2 forms of orienting overlapped in time. Experiment 2 discovered that another well-learned directional stimulus, an arrow, produced a different effect: Attention was shifted only volitionally to the predicted location. The authors suggest that because there is a neural architecture specialized for processing eyes, gaze-triggered attention is more strongly reflexive than orienting to arrows.

Attention, Researchers! It Is Time to Take a Look at the Real World:

Theories of attention, too often generated from artificial laboratory experiments, may have limited validity when attention in the natural world is considered. For instance, for more than two decades, conceptualizations of “reflexive” and “volitional” shifts of spatial attention have been grounded in methodologies that do not recognize or utilize the basic fact that people routinely use the eyes of other people as rich and complex attentional cues. This fact was confirmed by our novel discovery that eyes will trigger a reflexive shift of attention even when they are presented centrally and are known to be spatially nonpredictive. This exploration of real-world attention also led to our finding that, contrary to popular wisdom, arrows, like eyes, are capable of producing reflexive shifts of attention—a discovery that brings into question much of the existing attention research. We argue that research needs to be grounded in the real world and not in experimental paradigms. It is time for cognitive psychology to reaffirm the difficult task of studying attention in a manner that has relevance to real-life situations.

Attention to arrows: Pointing to a new direction

It was long believed that central arrows needed to be spatially predictive to produce a shift in spatial attention. Recent evidence indicates, however, that central spatially nonpredictive directional cues, like arrows, will trigger reflexive shifts in attention. We asked what this recent discovery means for past studies that used predictive directional cues such as arrows. Our findings indicate that predictive arrows produce attention effects that greatly exceed the individual or summed effects of reflexive orienting to nonpredictive arrows and volitional orienting to predictive numbers. This suggests that the especially large effect produced by predictive arrows reflects an interaction between reflexive and volitional orienting. Given the broad application of the predictive arrow cueing paradigm in both past and current research, the present data shed new light on a wide range of investigations, from psychophysical studies of basic attention to behavioural and neuroimaging studies of cognition and social development.

The eyes have it!: An fMRI investigation

For the past several years it has been thought that cues, such as eye direction, can trigger reflexive shifts in attention because of their biological relevance and their specialized neural architecture. However, very recently, reported that other stimuli, such as arrows, trigger reflexive shifts in attention in a manner that is behaviourally identical to those triggered by eyes. Nevertheless these authors speculated that reflexive orienting to gaze direction may be subserved by a neural system-the superior temporal sulcus (STS)-that is specialized for processing eyes. The present study presents fMRI data that provide direct and compelling empirical support to this proposal. Subjects were presented with fixation stimuli that, based on instruction, could be perceived as eyes or as another type of directional cue. Both produced equivalent shifts in reflexive attention, replicating Ristic et al. However, the neural systems subserving the two forms of orienting were not equivalent-with the STS being engaged exceptionally when the fixation stimulus was perceived as eyes.

The number line effect reflects top-down control

Recent evidence indicates that central directional stimuli, such as eyes and arrows, trigger rapid, reflexive shifts of spatial attention. A study by Fischer, Castel, Dodd, and Pratt (2003) suggested that a similar effect might also apply to central numbers, as if a digit’s meaning causes attention to be oriented to its relative position on a left-to-right mental number line. However, unlike central eyes and arrows, the orienting effect for central digits emerges slowly, suggesting that top-down endogenous processes may be mediating this effect. Here, we report a series of three experiments that strongly support this hypothesis. Experiment 1 replicated Fischer et al.’s left-to-right number line effect. Experiment 2 showed that this effect could be completely reversed by merely asking participants to imagine a number line running from right to left. Experiment 3 showed that a left-to-right number line effect could be abolished by presenting targets above and below central fixation, as well as to the left and right of center. Experiment 3 also showed that other mental sets, such as imagining a clock, result in attention’s being oriented in accordance with where the central digits are represented on a clock face. Together, these data indicate that the spatial representations and attentional orienting related to the perception of digits are both fragile and flexible and depend critically on the top-down spatial mental sets adopted by individuals.

Attentional Control and Reflexive Orienting to Gaze and Arrow Cues

A wealth of data indicate that central spatially nonpredictive eyes and arrows trigger very similar reflexive spatial orienting, although the effects of eyes may be more strongly reflexive (e.g., Friesen, Ristic, & Kingstone, 2004). Pratt and Hommel (2003) recently reported that the orienting effect for arrows is sensitive to arbitrary cue-target color contingencies; for example, an attentional orienting effect for blue colored arrows is evident only for blue targets. We reasoned that if the orienting effect elicited by eye direction is more strongly reflexive than the orienting effect elicited by arrow direction, it follows that eyes, unlike arrows, may trigger orienting effects that generalize across congruent and incongruent cue-target color contingencies. Replicating Pratt and Hommel (2003), we found that the reflexive attention effect elicited by arrows is specific to color-congruent target stimuli. The attention effect triggered by eyes, however, generalizes across color-congruent and color-incongruent target stimuli. These data support the hypothesis that eye direction and arrow direction trigger similar reflexive shifts in spatial attention, but that the attention effect triggered by eye direction is more strongly reflexive.

A new form of human spatial attention: Automated symbolic orienting

The control of human attention is typically conceptualized either in terms of exogenous automatic processes that are driven by external sensory stimulation or endogenous strategic processes that are driven by internal expectancies about events in the environment. However, this classic dichotomy has struggled to explain a wealth of new data demonstrating that behaviourally and biologically relevant visual stimuli, like arrow and eye direction, elicit shifts of spatial attention that on the one hand, appear exogenous, and on the other hand, endogenous. To address this issue, we used a double-cueing task that combined arrows with classic cues known to invoke either exogenous or endogenous orienting. Our data suggest that behaviourally relevant directional cues, like arrows, engage a new form of cortically mediated orienting—automated symbolic orienting—that operates independent of, and in parallel with, the two classic forms of exogenous and endogenous spatial attention.

Rethinking Attentional Development: Reflexive and Volitional Orienting in Children and Adults.

It is thought that a child takes the first 8 years of life to develop an adult-like volitional attention system. The data that support this belief, however, are based on studies that inadvertently measured a combination of volitional and reflexive attention, rather than volitional attention alone. What is immature then in children that are younger than 8 years of age? The volitional attention system or the manner that volitional and reflexive attention systems combine? We investigated this issue, with preschool and adult populations, by first isolating and then combining volitional and reflexive attention systems. Our results indicate that both volitional attention, and the way it combines with reflexive orienting, are immature in preschool children. We suggest that when volitional attention becomes adult-like its combination with reflexive attention will also become mature.

Automated Symbolic Orienting: The Missing Link

Attention can be controlled either exogenously, driven by the stimulus features, or endogenously, driven by the internal expectancies about events in the environment. Extending this prevailing framework, we (Ristic and Kingstone, 2012) recently demonstrated that performance could also be independently controlled by overlearned behaviorally relevant stimuli, like arrows, producing automated effects. Using a difficult target discrimination task within a double cuing paradigm, here we tested whether automated orienting engages selective attention, and if in doing so it draws on its own pool of attentional resources. Our data unequivocally support both possibilities, and indicate that human attention networks are uniquely specialized for processing behaviorally relevant information.