What Sign?

by Janine See

I was driving around Greenhills (particularly, through the streets surrounding Wilson) one morning when an MMDA officer suddenly stopped me. He told me that the street I was on was following a one-way traffic scheme, which I was not aware of. So I thought to myself, “What sign? There were no signs. This guy is clearly trying to get money from me.” I argued with the officer that there were no signs that said that this was a one-way street, because if there were, I surely wouldn’t blatantly disobey the traffic rules. He told me that there were signs on all the intersections crossing that street, and even pointed the next one out to me. I thought to myself, “How could I have missed all of those signs?”. Embarrassed, I apologized to the officer and tried to get out of getting a ticket and to my surprise and relief, he let me go and directed me towards Wilson. After that, I made sure to always be on the lookout for all the traffic signs I would pass by.

Many of us may have had similar experiences while driving. We think we are paying attention to everything there is on the road, but really, we miss many important signs or details that sometimes gets us into trouble. Psychologists call this Inattentional Blindness – the phenomenon of being unaware of obvious stimuli that we do not pay attention to. How we see things largely depends on what we focus on. Since there are so many things going on around us and in our heads, it is impossible to pay attention to everything all at once. Because of this limitation, it is inevitable that we will fail to notice some things, even if they were right in front of us.


A study by Most, Simons, Scholl & Chabris (2000) confirms that Inattentional Blindness happens even to objects that are very distinct in color, shape or path of motion. In the experiment, participants were asked to look at black and white shapes moving against a gray background and to focus on either the black or the white shapes and ignore the others. After many trials, a red cross was presented in the display and traveled across the screen for 5 seconds. At the end of the experiment, it was found that 1/3 of the participants did not notice the red cross at all. Even if the cross was distinctly different in terms of color and shape – two characteristics we assume would help the participants notice the cross, they still missed it. From this experiment, we can also conclude that when people are engaged in tasks that require a lot of attention, it becomes more difficult to focus on other things outside of the tasks, even if these seem to be very obvious.

This experiment is very similar to our experience of driving. Most of the time, our attention is focused on the road – looking out for moving cars, motorcycles and crossing pedestrians, watching the stoplight, avoiding potholes, etc., that we do not notice other road signs, even if they were in our field of view for a few seconds. Though these road signs are distinct, usually red or yellow against a gray cityscape, they can go unnoticed to a driver whose attention is focused elsewhere.

So the next time you get pulled over by an MMDA officer for ignoring a traffic sign, tell him a thing or two about Inattentional Blindness. (Kidding! Haha.) The lesson to pick up from learning about Inattentional Blindness is that now, we are more aware of the lapses we can have in seeing and paying attention to certain details, even if they were right in front of us. Though it is important to focus our attention to driving, we should also make sure that we allot some to looking out for road signs, as this will not only save us a lot of trouble, but more importantly, this can save lives.


[Calvin and Hobbes Pay Attention to Me]. (1989, October 26). Retrieved March 21, 2016, from https://www.pinterest.com/pin/173107179399257090/
Carpenter, S. (n.d.). Sights Unseen. PsycEXTRA Dataset.
Goldstein, E. B. (2013). Sensation and perception (9th ed). Belmont, CA: Wadsworth Cengage Learning.
Most, S. B., Simons, D. J., Scholl, B. J., & Chabris, C. F. (2000). Sustained Inattentional Blindness: The Role of Location in the Detection of Unexpected Dynamic Events. Psyche, 6(14). Retrieved March 21, 2016, from http://www.theassc.org/files/assc/2471.pdf

Binocular Disparity vs Luminance in Depth Perception

by Bella Tan

What is depth perception?

Depth perception is essentially the ability to see the world in 3-D. This means that we can tell how far objects are from each other or that we can tell that certain objects are closer to us than others.

How do humans perceive depth?

Humans use a number of different cues from the environment in order to perceive depth. These include oculomotor cues, or those based on our ability to sense our eye movements, monocular cues, or cues that will work with one eye, and binocular cues, or those that will only work if both eyes are looking.

Binocular disparity

Among the binocular cues is binocular disparity or stereopsis. The left and the right eye receive slightly different images from each other. The basic concept of stereopsis is that the difference between images in the left and right retina (a part of the eye where the image is formed) causes us to perceive depth. This principle is used in 3-D movies and television.

The use of stereopsis is commonly thought to be slow. Given this, some people have questioned how stereopsis functions in depth perception. Disparity has been compared to luminance (brightness) cues for depth perception. Caziot, Valsecchi, Gegenfurtner, and Backus (2015) studied these two together to determine when each cue is used.

The study

There were two conditions for the study. One condition relied on disparity cues, using crossed (to appear nearer) or uncrossed (to appear further) disparity from the background; the other condition relied on luminance cues, using disks of different brightness. The researchers showed two disks for each condition and instructed the participants to say which one was nearer.

The results? Although they found that the use stereopsis is slower than luminance processing (stereopsis takes at least 70 ms), the visual system does not need to wait for the integration period of stereopsis to end before it can utilize the information present. In fact, the use of information from stereopsis affects the observers’ reports at almost the same time as luminance does. In other words, stereopsis is not as slow as originally thought.

These results imply that stereopsis is important to depth vision, and that binocular disparities contribute much more to visual processing than people originally thought.


Caziot, B., Valsecchi, M., Gegenfurtner, K. R., & Backus, B. T. (2015). Fast perception of binocular disparity. Journal of Experimental Psychology, 41(4), 909-916. DOI: http://dx.doi.org/10.1037/xhp0000066

Garin, M. (2015, October). Understanding your depth perception. http://www.eyehealthweb.com/depth-perception/

Goldstein, E. B. (2013). Sensation and perception (9th ed). Belmont, CA: Wadsworth Cengage Learning.

Attention & Beyond

by Pam Torga

At this very moment, my mind is occupied by the thought of having to write a blog post. Yet I can also hear Beethoven’s Fourth Piano Concerto in the background; I can feel the swift and occasionally jouncing motion of the car I’m in; I can see a row of palm trees passing by, and; I am reminded of the opposing forces between my body and this arm chair because of the numbing sensation in my buttocks.

All these and more are happening around me as I write. And yet, I am not overtly paying attention to these other objects or events in my periphery. Instead, I choose to focus on the words I’m stringing together, the keys I’m pressing, and the thoughts I’m forming. Despite all that is happening around me, I continue to compose this blog entry because I choose to attend to it.

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Countless objects and events are present in the environment at any given moment. Try as you may, it is virtually impossible to notice and be fully aware of everything all at once. On top of that, the world around us is not without its endless sea of distractions. This makes the feat of paying close attention to a single object all the more fascinating.

What causes a person to draw his or her attention to an object or scene? How is this attention maintained? How am I resisting the urge to watch puppy videos on YouTube instead of cramming this blog? These are all baffling questions.

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Our physiological systems for attention are like state-of-the-art surveillance cameras and motion detectors. Yes, they’re cool but just like any security system, a figurative security guard operates on it. Let’s call him Frank, just like what Apollo Robbins called him. If anything interesting or potentially threatening comes up, Frank notices this in one of the screens and he possibly makes a report on it (stores a memory) for future reference. But Frank is only human (I mean, not really. But you get my point). He can’t monitor all the screens at once. So, if he is fixated at a pretty flower in one screen he may not notice that an alarm had just went off in a different area of the visual field due to a nearby bee posing danger.

Despite Frank’s slipups, he’s still pretty efficient. He has access to your memory and previous experiences which he can use to ascertain the survival value of what you’re currently attending to. If while looking at the flower, for instance, Frank decides to look up his previous reports in your database (memory bank), he may find that you once had an allergic reaction to a similar species of flower so he directs the “boys” (cortical structures) at the motor system to steer you away from the threat. It is important to note, however, that while Frank searches in the filing cabinet of reports (retrieves a memory), he is unable to notice the precipitating events in the surroundings (Imagine Frank having to turn his back from the monitors to sort through the “filing cabinet” of memories). All in all, Frank, our supervisory attentional system, guides our attention and helps us effectively interact with our environment, with a few inevitable setbacks.

Reportage activitŽs Spie au Casino Barrire Toulouse

Perceptual psychology explains that attention is directed to those objects or scenes that are critical to one’s survival and/or which bear meaning to the observer. Take for instance my rambling of events at the beginning. I could just as well have described the color of the pastures or the large rock sitting beside the road, but I did not. My surroundings could have been described in countless other ways, but I instead heard Beethoven and remembered my buttocks. Why? Because at that particular moment, my sensory modalities or cognitions were simply attuned to noticing what I had noticed.

The mechanisms behind attending are not always clear-cut. We overlook and fail to attend to certain objects or scenes for numerous and probably overlapping reasons. For instance, my failure to notice the grass and rocks earlier may have been because they were not as salient as all the other things I instantly and easily perceived (physical salience). Or maybe it’s the fact that such objects don’t elicit the same emotional response as music and travelling at high speeds do (affective salience). Or perhaps I just don’t have a thing for grass or rocks (semantic salience). Equally valid explanations such as these illustrate how multifaceted and dynamic the process of attending is.

Another reason why we can easily attend to a specific object but, at other times, find it difficult to notice anything else is because the perceptual system has a limited capacity for processing information. Each one of us has a certain perceptual capacity—like a cup for holding our “attentional juice.” The way this cup is filled depends on the amount of attention we direct to a task at hand. For instance, when I’m reading a book for leisure, my cup is roughly half-full. Although I am focused on what I’m reading, I may still notice anything new or salient in my environment such as the scent of food in the kitchen or the sound of my pets barking in the garden. Because reading is a relatively easy task, this leaves room in my cup, permitting me to possibly attend to other things.

On the other hand, if for some strange reason I’m doing burpees while subtracting increments of 7 from 1000, the glass would definitely be full. You can imagine that a person doing such a difficult task would have used up all her resources, rendering her vulnerable to overlooking even the most eye-catching of objects (This is called inattentional blindness). This means even if a salient object such as a pink, glittery Chihuahua passed by in front of me, it is unlikely for me to have noticed it because my glass can only hold so much. We focus on specific objects or events while ignoring everything else in order to prevent overloading our perceptual systems. In other words, we attend only to a certain extent so that our cup won’t overflow with “attentional juice.”

I earlier mentioned that I don’t have a thing for grass or rocks. What I meant by this is that some objects, such as grass and rocks in my case, do not momentously bear any meaning to me. Semantic salience operates on this fundamental idea that meaning can attract a person’s attention. And because there are large variations between people, there are also appreciable variations in how people scan scenes based on what they value.

Semantic salience and stimulus salience (the fact that objects with particular physical properties become more conspicuous than others) have the capacity to direct our attention. An important question therefore is, to what extent is visual attention driven by the meaning of individual objects, rather than by their visual appearance? De Groot, Huettig, & Olivers found that timing is apparently a crucial factor in the occurrence and strength of semantic influences on how we attend to objects or scenes. We substantially orient ourselves toward objects that are related by meaning compared to objects that are visually related. More importantly, attention is driven by our preferences that dynamically shift between visual and semantic representations, with each of these mostly operating independently.

An interesting insight on the relationship between meaning and attention is that they appear to bring about a vicious cycle. If attention is captured by meaning and what we pay attention to gains enhanced perception, then those objects which initially already bear meaning are more likely to be noticed and their significance in our cognition is consequently elaborated. Such that when the observer encounters this object again with its added significance, he or she will again be more likely to pay attention to it. For short, we pay attention to something because of its meaning and, something holds meaning because we pay attention to it.

If you have ever tried listening to your professor’s lecture in class (which I hope you have), you may have noticed that your attention seems to be an “on-off” thing. What causes your attention to switch “on”? What causes it to switch “off”?

I’m not sure if this applies to everyone, but I usually listen in class when I find the topic rather interesting (semantic salience) or when I’m in good mood. Our mood or affective states apparently also influence our attention. Our knowledge of the relationship between what we feel (mood) and what we think (cognition) has been extended to understanding the important implications for understanding the social cognitive consequences of positive mood states.

Interestingly, Sedikides found that the effects of mood on attention have nothing to do with the self-focused nature of the event which caused the mood. He also proposed a model to account for the relation between mood and attention focused on oneself. According to the model, a sad mood produces momentary negative self-evaluation, which in turn creates uncertainty about one’s self-worth. This instigates self-perception processes that result in heightened self-focused attention. In contrast, a happy mood leads to certainty about one’s self-worth, which allows an extroverted orientation. Cool, good vibes begets good vibes!

Through experimentation, Sedikides also determined that a sad mood tends to induce self-focused attention, whereas a happy mood tends to elicit external-focused attention. What are the implications of this in the classroom setting? When you’re feeling blue or just not “in the mood”, you are likely to direct your attention to yourself, therefore, causing to be more aware of self-referent information. You could start forming thoughts like “I’m so sleepy, I want to sleep.” or “Ugh, I suck at this class.”—thoughts that revolve around you. In contrast, when you happen to have a sunny disposition that day in class, you are more likely to focus on the things around you. You could notice the beautiful weather outside your classroom window, your seatmate’s super OC notes and, hey, maybe even your professor lecturing  right in front of you!

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Being happy could ~possibly~ make you listen in class!

Another great thing about being in a good mood is that positive mood states are thought to sensitize individuals to rewards in their environment. This is probably so that we can orient ourselves to beneficial decision making and behavior when our eyes are “on the prize.” From a selective attention standpoint, such mood-related effects should be associated with selective attention preferences toward rewarding stimuli. In other words, we probably feel that way because out attention is drawn to the rewarding things around us. So, next time you’re in a positive mood, notice that you tend to pay more attention to things that are likewise imbued with positivity.

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This dog’s positive mental state is drawn to the rewarding stimulus of a vacuum rub.

Despite the massive role of semantic salience in attention, even the most important things to us like our valuables and money can slip our mind. How can something so meaningful and critical to our day-to-day functioning be overlooked? The simple answer: Attention isn’t perfect. Apollo Robbins, hailed as “the greatest pickpocket in the world,” demonstrates how this is so. In his talk at TEDGlobal 2013, Robbins discusses the quirks of human behavior, showing how the flaws in our perception make it possible to swipe a wallet and leave it on its owner’s shoulder while they remain clueless.

The study of attention has yielded numerous terms for describing the multitude of ways we are oriented to in the surroundings. One is exogenous orienting, which refers to reflexively or externally generated shifts of attention to perceptually relevant stimuli. In contrast, endogenous orienting refers to voluntarily or internally generated shifts of attention. Operationally, both endogenous and exogenous modes of orienting increase the speed and/or accuracy of responses to targets presented at the attended location. Another way of describing how we attend is by indicating that we do so either overtly or covertly. Overt orienting refers to relative improvements in information processing at locations to which the eyes are or were directed, while covert orienting refers to improvements in information processing in the absence of eye movements. The fact that there are different ways of attending to objects or scenes hints that different physiological and cognitive processes are at play for each mode of orienting.

Did you know that your eyes sometimes don’t even have to be prepared to move in order to pay attention? I didn’t—that is until I had learned about the experiments of MacLean, Klein, & Hilchen, where they disproved the two predictions of the oculomotor readiness hypothesis. Basically, they found that (1) shifts in covert attention are not accompanied by preparedness to move one’s eyes to the attended region, and (2) preparedness to move one’s eyes to a region in space is also not accompanied by a shift in covert attention to the prepared location. Basically, MacLean, Klein, & Hilchey found that individuals experienced covert capture without accompanying eye movement and experienced eye movement without accompanying covert capture.


This dog is either demonstrating inattentional blindness or terribly failing to take action from input derived from overt orienting.

For the most part of my incoherent blog, we’ve discussed attentional capture—the unintentional focusing of attention which interrupts other processing.

Reflected light carries a lot of information for the human visual system to process at once. Attention’s role in the perceptual process is to make sure that some locations or objects are selectively prioritized even if at the expense of others. A fundamental problem for the visual system is to decide which locations or objects deserve priority. Often, priority is task or goal dependent. For example, drivers might preferentially attend to red objects because of the importance of brake lights, stop lights, and stop signs. Bicyclists are wary of looming objects (pedestrians, trees). People walking home late at night are especially attuned to sudden motion. Although top-down expectations and goals help determine the focus of attention, some visual events seem to attract attention regardless of the current task; they capture attention. For example, when someone is directing attention to a book on a shelf, an object that suddenly appears (say, a cat jumping onto the shelf) will draw attention away from the book, capturing attention. Sudden changes in the world are likely to be important and might never be attended if priority were governed solely by top-down goals.

What types of stimuli capture attention? According to the most prominent theory, the only kind of stimulus that captures attention is the appearance of a new visual object. Under this new-object hypothesis, the locations of visible objects are indexed when an observer first views a scene. The visual system prioritizes new objects because new objects provide novel information that is often behaviorally relevant. According to an alternative view, the transient hypothesis, some types of simple luminance (amount of light) and motion transients capture attention, whether or not they are associated with a new object. For example, although the cat jumping onto the shelf is a new object, its appearance also coincides with a strong motion transient. By this account, it is this motion signal that draws attention, not the fact that the cat is a new object in the scene.

In contrast, the new-object hypothesis maintains that attention capture is driven solely by the presence of a new object, and not by the luminance or motion transients associated with an object’s appearance; transients alone are not sufficient to capture attention. This means that a dog that moves into view should capture attention by virtue of its status as a new object, but a previously visible dog that introduces an equivalent motion transient should not capture attention.

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This dog would unfailingly capture my attention whichever hypothesis you use.

The visual system relies on several heuristics to direct attention to important locations and objects. One of these mechanisms directs attention to sudden changes in the environment. Previous work suggests that attentional capture is mediated by a mechanism that detects the appearance of new objects. Other findings say otherwise: New objects are not necessary for attention capture. The body of research on stimulus-driven attentional capture concludes that new objects do not capture attention unless they created a strong local luminance transient. This means that a new object attract attention not because the visual system is sensitive to new objects but because it is sensitive to the transients that new objects create.

Attention selects which aspects of input from our senses are brought to our awareness. To promote survival and well-being, attention prioritizes stimuli both voluntarily, according to context-specific goals (e.g., searching for your car keys), and involuntarily, through attentional capture driven by physical salience (e.g., looking toward a sudden noise). Valuable stimuli are known to strongly affect our voluntary attention. However, stimuli that are high-value although seemingly irrelevant to the context may still capture attention as a consequence of reward learning. Andersen (n.d.) investigated on this form of attentional capture driven by the stimuli’s value. He found that vulnerability to such value-driven attentional capture varies across individuals in relation to memory capacity and trait impulsivity. With this, Andersen one day hopes that “this unique form of attentional capture may provide a useful model for investigating failures of cognitive control in clinical syndromes in which value assigned to stimuli conflicts with behavioral goals (e.g., addiction, obesity).”

After reading this blog, I hope you’ve realized the power and great potential of attention in influencing various facets of our life. Because of its largely enigmatic nature, attention is truly one of the most intriguing perceptual phenomena that most of us take for granted. The importance of attending to objects and scenes is certainly not limited to its role in efficient interaction with the environment. With all that we have discussed, it’s clear that attention inevitably controls our perception of reality.


Anderson, B. A. (n.d.). Value-Driven Attentional Capture Is Modulated by Spatial Context. PsycEXTRA Dataset. doi:10.1037/e528942014-042

Goldstein, E. B. (2010). Encyclopedia of perception. Thousand Oaks, CA: Sage Publications.

MacLean, G. H., Klein, R. M., & Hilchey, M. D. (2015). Does Oculomotor Readiness Mediate Exogenous Capture of Visual Attention? PsycEXTRA Dataset. doi:10.1037/e633262013-724

Sedikides, C. (1992). Mood as a determinant of attentional focus. Cognition & Emotion6(2), 129-148. doi:10.1080/02699939208411063

TED Talks. (2013, September 13). Apollo Robbins: The art of misdirection [Video file]. Retrieved from https://www.youtube.com/watch?v=GZGY0wPAnus