Funded Grants

Revealing the Perceptual and Neural Mechanisms of First Impressions

A couple of years ago, Taco Bell had a billboard advertisement that depicted the arm of a man, positioned almost vertically, holding a taco. Although I did not mind Taco Bell as a fast-food option, I found this ad exceptionally aversive. Intrigued by my strong feelings against it (which were nothing like the usual inattention that most other advertisements receive), I scrutinized it, but to no avail. Containing only an appetizing taco, with a clean and aesthetic hand holding it, this ad, and my obsession with it, remained a puzzle. Then one day I was driving and about to merge with traffic, just ahead of an approaching bus. Glancing ever so briefly to the left and returning my gaze to the right, I was left with the impression that the bus carried an ad on its side, depicting a cobra snake in a ready-to-bite position. So I looked again, and noticed that it was the Taco Bell ad. The configuration of the arm with the taco was associated in my mind with a snake. Studying nonconscious perception at the time, I interpreted this observation as the closure for which I was looking: visual elements in the picture influenced my impression about it non-consciously, such that my attitude towards this ad was negative. At some level it reminded me of an intimidating snake. The first impression of repulsion persisted, although consciously I realized there was nothing negative about the picture.

This is an example of a phenomenon that often occurs in everyday social interaction with the environment: we form our first impressions of people and objects very early (first couple of hundred milliseconds), without being aware of the sources that influenced these impressions. These first impressions then persist, often in spite of subsequent perception of contradictory information.

A great deal has already been revealed about the social nature of first impressions. Very little, however, is known about the perceptual and cortical basis underlying the formation and persistence of first impressions. What are the actual physical elements of an object that make us like it, hate it, or be afraid of it? What brain processes facilitatethe blazingly fast formation of first impressions, and what in the brain mediates the persistence of early impressions?

First impressions are often accurate, and they facilitate our survival and interaction with the environment. For example, humans and monkeys are excellent at judging threat, dominance and hierarchy following a single glance at a picture. Some first impressions, however, are less accurate and subsequently misguide our behavior in a less desirable manner. For example, in a court situation, it has been shown that defendant attractiveness is associated with judges levying smaller fines in actual cases.

The research proposed here will expose the perceptual and neural factors that affect the formation and the (non-flexible) persistence of first impressions. Therefore, in addition to understanding the perceptual and neural bases of first impressions, the studies proposed here have direct social implications.

Because the activation of first impressions is so rapid, it is reasonable to suspect that the perceptual features that mediate their formation are processed quickly, and therefore are either primitive in their structure, or analyzed on a coarse level. If we could define those physical elements that non-consciously affect our first impressions and attitudes, we may be in a better position to modulate their influence on our life.

To address these issues, I propose combining behavioral experiments that apply theory and paradigms from perception and cognitive neuroscience with recently developed brain imaging techniques. Specifically, the studies will focus on the formation and persistence of first impression.

The first step will be to reveal the 'vocabulary' of perceptual primitives that determine first impressions. These are the specific physical properties in the appearance of a person or an object that non-consciously shape our attitude. For example, studies with brief visual presentations of various pictures indicate that observers judge figures containing sharp edges as possessing aggressive traits, whereas the same figures are judged as more positive when the edges are smooth. Another example of a basic physical feature that conveys a complex trait was reported in a study where black color of sports uniforms was associated with subjective perception of aggressiveness.

To define this "list" of perceptual primitives that influence the formation of attitudes and impressions, we will use subliminal visual priming. We will very briefly present a visual image that may have an emotional valence, such that observers are not aware of it. Immediately following this subliminal presentation, we will present a neutral target object that is readily recognizable. Participants will then rate how much they like the target picture, or how much they think it is threatening, or how much they would like to own the target object.

In searching for impression-forming features, we will focus on stimuli with social and survival-related significance, such as patterns that convey a threat, patterns with sharp vs. smooth edges, animals, food, facial parts, and faces that may be associated with specific stereotypes. If the prime stimulus (i.e., the subliminal pattern that precedes the target) affects participants' liking judgments regarding the neutral target, we will infer that this is an impression-forming feature.

In a second set of experiments, we will use brain imaging to examine our hypothesis regarding how these impression-forming features are analyzed and propagated in the brain. The gist of this hypothesis is that our brains have evolved to analyze information that represents a possible danger more quickly than neutral information. Incoming sensory information is analyzed thoroughly, on a fine-grained level, along a hierarchy of cortical regions. At the same time, however, critical information may directly be relayed in a coarse form via 'cortical shortcuts' from low- to high-level regions to guide a specific behavior. For example, because sharp edges may reliably predict dangerous objects, quickly analyzing and avoiding them may facilitate survival. Or, if we encounter a lion in the woods, we should be able to act based on coarse-level information that conveys the general shape, rather than wait until all the fine details (e.g., color and texture) have been analyzed. We will identify these 'cortical shortcuts,' or direct pathways, using recently developed techniques for combining multiple brain imaging methods. This combination is powerful because it takes advantage of the spatial resolution of functional Magnetic Resonance Imaging (fMRI) and the temporal resolution of magnetoencephalography (MEG) so that we can monitor brain activity within a spatial resolution of about 1 millimeter and a temporal resolution of about 1 millisecond.

We will study these cortical shortcuts by manipulating parameters that are expected to modulate their use, while imaging the corresponding events in the brain. First, we will define and characterize these shortcuts, which will be done by comparing the cortical dynamics during the perception of impression-forming stimuli and the perception of neutral stimuli. Then, in a second set of experiments, we will correlate the activation of the cortical shortcuts, as measured with brain imaging, to level of subjective attitude, as measured behaviorally. Consequently, these experiments will allow a characterization of the cortical 'shortcut' pathways that facilitate the formation of first impressions by rapidly relaying critical information to high-level regions in the brain.

Finally, we will address the issue of persistence. Persistent first impressions have a clear advantage for survival. For example, if some sensory cues reliably indicate that something in our environment is dangerous, it is in our best interest to remain alert while in its neighborhood. In other contexts, however, some first impressions can be misleading and need to be updated with the perception of new information. Revealing the aspects that modulate the persistence of first impressions, therefore, has important implications for everyday life in that such an understanding may allow us to monitor their influence. We will examine the environmental factors and brain mechanisms that mediate its magnitude and 'life-span.' This effort, too, will be divided between behavioral experiments and the use of brain imaging. Factors that we predict may have the potential to modify persistent first impressions include whether the participants are aware of the source of the influence on their impression formation, and the type of the impression (e.g., positive or negative). We will manipulate those factors and study their affect on the persistence of first impressions.

In addition, we will examine potential methods for modifying persistent first impressions. For example, we will try to modify a certain impression (e.g., negative) by repeatedly associating it with an opposite impression-forming feature (e.g., positive). Not only do such methods have widespread social implications, they will also allow us to image neural processes involved in the formation, persistence and modification of first impressions.

By bridging between perception, cognitive neuroscience, and social behavior, it is expected that this research program will illuminate the underpinning of first impressions, and increase our appreciation of their influence on social interaction in everyday life.