Chapter 6: Attention and Visual Perception

Introduction

In this chapter, we will consider the relationship between attention and visual perception. To begin, let's explore Visual Search Tasks, which are commonly used in the study of attention and perception and serve as an apt introduction to the way attention operates in complex visual environments.

Visual Search Tasks: Seeking a Needle in the Haystack

Imagine you're at a bustling carnival, trying to find your friend in a lively crowd. The scenario might remind you of playing "Where's Waldo?" as a child, where the goal is to spot Waldo, a distinctive character, hidden amidst a sea of people dressed in various colors and patterns. If Waldo were the only person in the crowd wearing a red and white striped shirt while everyone else sported solid black attire, finding him would be relatively effortless. This scenario exemplifies the essence of a visual search task.

Visual Search refers to our innate ability to locate a specific target item within a visual field containing numerous distractors. Whether it's finding a friend at a carnival or identifying a familiar face in a crowded room, visual search tasks are an integral part of our everyday lives.

In the example of locating your friend, the red and white striped shirt becomes the "feature" that distinguishes your friend from the rest of the crowd, who are all wearing black. This type of search, known as a feature search, is characterized by the presence of a single distinctive feature (color, shape, or orientation) that sets the target apart from the distractors. Our visual system can efficiently detect this unique feature, guiding our attention to the target.

However, not all visual searches are as straightforward as spotting Waldo's distinct shirt. In more complex scenarios, we may need to perform what's called a conjunction search, where we're looking for a combination of features. For instance, finding your friend in a crowd where everyone has varying clothing colors and patterns becomes a more challenging task, akin to searching for a particular item in a cluttered scene.

In a conjunction search, our attention must bind together multiple features (e.g., color and shape) to identify the target accurately. This process demands more cognitive effort and time compared to a feature search.

Figure 6.1

Anne Treisman's Feature Integration Theory: The Glue of Visual Perception

Anne Treisman's theory posits that our attention plays a crucial role in binding visual features together. Imagine you're searching for a red inflatable lobster in a pool filled with pool toys of various colors and patterns. In this scenario, the red color and lobster shape serve as the distinctive features of your target. If there is only one red item in the pool then this feature guides your attention, allowing you to pick it out effortlessly.

Feature Integration Theory suggests that when we search for a target defined by a single feature (like color), our attention efficiently detects that feature when none of the distractors share this visual feature. Here the time to find the target will not increase as the number of distractors increases. However, when the target is not unique on any single visual feature then we're dealing with a conjunction search where we must combine multiple features (e.g., color and shape). This would happen if you were searching for a red inflatable lobster in a pool filled with red, brown, and green pool toys that were shaped like a lobster, moose, or tree and where you had all nine color- shape combinations. In this situation our attention becomes the "glue" that binds these features (color and shape) together. Since feature binding takes time to complete reaction times to find the target will linearly increase as the number of distractors in the display increases.

Inattentional Blindness: The Gorilla in the Midst

Now that we've explored how attention plays a vital role in visual search tasks, let's look into another intriguing phenomenon called Inattentional Blindness. This phenomenon highlights the idea that attention is crucial for perception.

Imagine you're engrossed in a riveting conversation with a friend while watching a basketball game. As you focus intently on the game, you may fail to notice a person in a gorilla suit casually strolling through the basketball court, right in the middle of the action. This startling oversight is a classic example of inattentional blindness.

Inattentional blindness occurs when we are so absorbed in one task or aspect of our visual environment that we completely miss something unexpected and unrelated that is plainly visible. The gorilla in the basketball scenario exemplifies how we can be blind to information that doesn't align with our current focus.

Change Blindness: Failing to Detect Subtle Alterations

Continuing our exploration of attention's impact on perception, let's discuss another intriguing phenomenon known as Change Blindness. Change blindness is the finding that people are remarkably poor at detecting changes in the visual environment and illustrates that our awareness of subtle changes are not shielded by allocating attention to the object that might change.

For example, imagine you're approached on a college campus by a stranger asking for directions. Then in the middle of the conversation a group of people walk between you and the stranger. The people are carrying a door and unbeknownst to you the person you’re talking with is replaced by a completely different person and all of happens when the door passes between you and the stranger. Once the people pass by you are then left talking with a completely new individual. Although many people believe they would notice this change, after all you were attending to the person who was asking for directions, Simons and Levin (1998) find that many people fail to detect this change.

Change blindness occurs when we fail to detect significant changes in our visual field, even if we are actively looking at the scene. Our attention is selective, and it often prioritizes the most relevant or salient information, causing us to overlook alterations that are not immediately pertinent to our current focus.

The Attentional Blink: Blink and You'll Miss It

Our journey through attention and visual perception would be incomplete without discussing the Attentional Blink, an intriguing cognitive phenomenon that provides insights into how quickly we can allocate our attention to rapidly presented information.

Imagine you're watching a rapid sequence of images, and your task is to identify specific targets within this sequence. For instance, you're asked to find a fruit (an apple or a banana) and then a timepiece (either a digital or an analog watch). These targets appear in quick succession.

What researchers have discovered is that after successfully identifying the first target (T1) (e.g., the apple), there's a notable tendency to miss the second target (T2) (e.g., the digital watch) if it follows closely behind. This phenomenon is termed the "attentional blink." However, when T2 is presented immediately after T1 accuracy is often quite high (known as "Lag 1 sparing"). Two theories have been proposed to explain lag 1 sparing and the attentional blink results.

In the attentional gate theory attention is viewed as a gate that lets T1 pass through. When T1 enters through the gate we close the gate to process the item. If T2 is shown immediately after T1 it gets though our attentional gate and is processed along with T1. However, if T2 appears at a slight delay it is blocked from entry and T2 stimuli are missed until the gate reopens.

The temporary loss of control theory proposes that attention is allocated to the target category but when we encounter a distractor the system's control over its attentional focus is momentarily weakened. This disruption in attentional focus disrupts processing and T2 may be missed until our focus on the task is restored.

These two explanations make different predictions of what will happen when people are presented with multiple targets. For example, if people are looking for letters and are shown the following sequences: 14589R7J04723 vs. 14589RQJ04723 (these items would be shown one at a time: 1 followed by 4, followed by 5, followed by 8, etc.) performance at recognizing the "J" should differ depending on whether a letter had preceded this (second example where Q is presented before the J) or whether a number had preceded this (first example where 7 is presented before the J). The gate theory predicts no difference between these examples since the J follows the R by the same duration. The results show that performance is worse when a distractor (7) precedes T2 as predicted by the temporary loss of control theory (i.e., accuracy at identifying the “J” is worse in the first example where it follows a 7 than the second example where it follows a Q).

The attentional blink highlights the limitations of our attentional capacity when it comes to rapidly processing and identifying multiple targets in a short timeframe. It reveals that there is a brief period during which our attention seems to be momentarily "blinded" or unavailable for processing subsequent information.

Cultural Differences in Attention and Perception

Research by Richard Nisbett and colleagues has shown that East Asian participants tend to have a more holistic cognitive style, while Westerners lean toward an analytic style. These cognitive differences manifest in how individuals process visual scenes. Western participants typically focus on prominent objects, while East Asian participants pay more attention to the background context and relationships between objects and the background. These differences have been observed in various experiments, such as describing vignettes and change blindness tasks. Nisbett suggests that East Asian participants may have broader attentional foci and excel in encoding spatial relationships and detecting changes in contextual aspects of scenes, while Western participants may excel when finding changes in focal objects.

Conclusion

In conclusion, this chapter shows how attention shapes our perception, enabling us to excel in visual search tasks, yet also revealing the limitations of our awareness in phenomena like inattentional blindness, change blindness, and the attentional blink. Anne Treisman's Feature Integration Theory has provided us with a valuable framework for understanding how our attention binds together the rich tapestry of visual features that surround us. As we navigate our complex visual world, it becomes increasingly clear that attention is not merely a passive spotlight; it is active mechanism that integrates visual information, blocks distraction, and may have temporal limitations.