Posts Tagged ‘Perception’

Healthy Memory Overview

July 31, 2019

This blog was begun in October 2009, and all the posts are still accessible. The first post was “The Seven Sins of Memory.” So this blog is almost ten years old. Theories of memory and HM’s knowledge of memory have increased and improved since then. This is the first in a series of blogs providing advice on the best way to think about memory.

The first question to ask is “What Is Memory?” When many people think of memory they regard it as storing things they need to regurgitate on a test, or on forgetting items to pick up at a store or an important appointment. But memory is much, much more than that.

Memory is cognition. Our memory enables us to think. It influences perception. It produces and remembers emotions. It influences our physical performance.

Most importantly, it enables us to travel in time. It enables us to travel back in time so we can make use of our prior experience to address current situations.

In doing so, we use our memory to travel forward to the future. What will be the nature of the problem? What do we know that we can retrieve to help us decide how to address this future problem? Then we can imagine future actions in future scenarios to see how they’ll pan out. So we mentally travel to the past to address problems and travel to the future to see how these scenarios will likely play out.

The problems we address vary from how to most efficiently plan and execute a shopping trip, to how to plan and prepare for college, a career, investments, retirement and so forth. As an informative exercise try monitoring your mental processes to see how much time you spend in time travel.

In short, memory is critical to cognition, which makes it central to how we live our lives. How successful and fulfilled we feel is very much determined by a healthy memory.

So a healthy memory is of utmost importance. This blog addresses not only how memory works, but how best to make and maintain a healthy memory.

© Douglas Griffith and, 2019. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.

The Myers-Briggs Type Indicator (MBTI)

March 23, 2019

This is the seventh post in series of post based on a book by Stephen Kosslyn and G. Wayne Miller titled “Top Brain, Bottom Brain.” The subtitle is “Harnessing the Power of the Four Cognitive Modes.” The MBTI is the bane of most psychologists. Once people know that you are a psychologist, it is not unlikely that they will expound on the marvels of the MBTI. Moreover, it is used in some Intelligence Agencies. According to one estimate, about 2.5 million people a year take the test. So HM never resists the opportunity to set people straight on the MBTI.

The MBTI is scored on four dichotomous dimensions:

Extraversion vs. Introversion, which focuses on what sort of activities energize a person: Extraverts draw energy from interacting with others and are dampened down when they spend a lot of time alone; the opposite is true for introverts.

Sensing versus Intuition, which focuses on what a person prefers to pay attention to: Sensing types are very concrete, preferring factual material that is predigested and handed to them instead of material that requires them to abstract and organize meaning to distill underlying principles; the opposite is true for intuitive types.

Thinking versus Feeling, which focuses on decision-making preferences: Thinking types are logical, systematic and relatively detached when making decisions; feeling types are more inclined to rely on emotional considerations and to strive for overall “harmony.”

Judging versus Perception, which focuses on preferences for how to act in the world at large: Judging types like to plan and organize; perceiving types prefer to be open to new possibilities as they arise.

On the face of it these dimensions seem reasonable, and it is clear why this test has intuitive appeal.


The test was not developed by psychologists, statisticians, or any type of professional. Katherine Cook Briggs and her daughter Isabel Myer Briggs began to develop this test during WW2 as a tool to help women discover which wartime jobs would be most comfortable and appropriate for them. The test MBTI was the tool. Here are the problems:

It is not based on science; instead, it largely grew out of Jung’s theory of psychoanalysis, which he formulated on the basis of intuition and clinical observations.

Some of the assumptions that underlie the test appear to be contradicted by scientific findings. For example, the MBTI is scored as if “intuition” is distinct from “feeling”—but much evidence now indicates that emotion often underlies hunches.

When items are analyzed so that the underlying factors can be discovered, the results do not correspond to the four dimensions posited by the theory.

When scores are analyzed, they do not cluster around the middle of the dimensions.

in spite of the fact that the test developers stressed that their test is designed to assess preference and not abilities, researchers have examined whether scores predict performance—and they do not consistently do so. Moreover, when they do predict performance, this may be a consequence of the correlation between the MBTI scores and other measures.

Numerous researchers have found that the test has poor reliability. Test takers often get a different score when they take the test a second time.

In addition to the MBTI the authors of “Top Brain, Bottom Brain” also debunk a view of personality that focuses on the anatomical distinctions between the left and right halves of the brain. Although there are differences, under normal circumstance the two halves do interact, and way too much has be made of this theory.

The Signatures of Conscious Thought

April 5, 2016

“The Signatures of Conscious Thought” is the fourth chapter of “Consciousness and the Brain:  Deciphering How the Brain Codes our Thoughts” is an outstanding book by the French neuroscientist Stanislas Dehaene who is the Chair of Experimental Psychology at the College of France.  This is the fifth consecutive post on this outstanding book.  In this chapter Dr. Dehaene discusses four reliable signatures of consciousness—physiological  markers that index whether the participant experienced a conscious percept.

The first signature is a sudden ignition of parietal and prefrontal circuits that is caused by a conscious stimulus (remember that the participant indicates whether the stimulus is conscious).

The second signature is found in the EEG in which conscious access is accompanied by a slow wave called the P3 wave, which emerges as late as one-third of a second after the stimulus.

The third signature is the result of conscious ignition that also triggers a late and sudden burst of high frequency oscillations.

The fourth signature  consists of many regions exchanging bidirectional messages over long distances in the cortes, which form a global brain web.

The conscious brain can perceive only a single chunk at a time.  Working memory rehearses these chunks to keep the active so they can be further processed.  The processing of a second chunk can be delayed if it occurs prior to the processing of the first chunk.  This is known as the psychological refractory period.

We can process a stimulus before we become consciously aware of the stimulus.  For example, if we place a hand on a hot stove, we’ll take it off the stove before we consciously perceive the pain caused by the hot stove.

Consciousness lives in  loops of reverberating neuronal activity, circulating in the web of our cortical connections, causing our conscious experience.

fMRI and scalp recording of brain potentials catch just a glimpse of the underlying brain activity.  Explorations of the third and fourth signatures require electrodes being placed directly inside the brain.  Such implantations of electrodes are indicated for certain epileptic patients, so science can capitalize on victims of this unfortunate malady.  I hope it provides some satisfaction to these patients that the data that is derived from these electrodes is greatly advancing science.

Subliminal stimuli can propagate  deeply into the cortex, but this brain activity is strongly amplified when the threshold for awareness is crossed, thus yielding reliable and valid signatures of consciousness.

How the Illusion of the Present is Created

January 20, 2015

This blog post is based in large part on an article in New Scientist (10 January 2015, 28-31) by Laura Spinney. Although we feel like we are living in the present, we need to construct the present from what has happened in the recent past. First of all, we need to work with data processed by our senses. Different senses process information at different rates. For example, the auditory system can distinguish two sounds just 2 milliseconds apart, whereas the visual system requires tens of milliseconds. It takes even longer to detect the order of stimuli. There is evidence that even at the subconscious millisecond level, our brains make predictions. For example, when we watch a badly dubbed movie, our brains predict that the audio and visual streams should occur simultaneously, but if the lag between them does not exceed 200 milliseconds we stop noticing that the lip movements and voices of the actors are out of synch. Our brains need to blend these different sources of information coming in at different rates into a coherent present, so we can deal with what is happening in what appears to be now, but is actually the future.

Marc Wittman of the Institute for Frontier Areas of Psychology and Mental Health in Freiberg, Germany has developed a model of how this process occurs by drawing on a very large mass of psychophysical and neuroscientific data (Frontiers in Integrative Neurosciece, vol. 5, article 66). He believes that there are a hierarchy of nows, each of which forms the building blocks of the next, until the property of flow emerges into an the illusion of the present.

Virginie van Wassenhove and her colleagues at the French Medical Research Agency’s Cognitive Neuroimaging Unit in Gif-sur-Yvette have been investigating how the brain might bind incoming information into a unified functional moment. They exposed people to sequences of bleeps and flashes. Both occurred once per second, but 200 milliseconds out of synch. Brain imaging was used to reveal the electrical activity produced by these two stimuli. This consisted of two distinct brain waves, one in the auditory cortex and the other in the visual cortex, both oscillating at the rate of once per second. At first the two oscillations were out of phase and the research participants experience the light and sound as being out of synch. But later they reported starting to perceive the beeps and flashes as being simultaneous, the auditory oscillation became aligned with the visual image. So our brain seems to physically adjust signals to synchronize events if it thinks that they belong together (Neuroimage, vol 92, 274). So it appears that even at the subconcious level our brains are choosing what it allows into a moment. But according to Whittman this functional moment is not the now of which we are conscious. This comes at the next level of his hierarchy, the “experienced moment.”

This experienced moment seems to last between 2 and 3 seconds. David Melcher and his colleagues at the University of Trento, Italy provided a good demonstration of this moment. They presented research participants with short movie clips in which segments lasting from milliseconds to several seconds that had been subdivided into small chunks that were shuffled randomly before presentation. If the shuffling occurred within a segment of 2.5 seconds, people could still follow the story as if they hadn’t noticed the switches. But the participants became confused if the shuffled window was longer than 2.5 seconds (Plos ONE, vol 9, pe102248). So our brains seem able to integrate into a cohesive, comprehensible whole within a time frame of up to 2.5 seconds. The researchers suggest that this window is the “subjective present,” and exists to allow us to consciously perceive complex sequences of events. Melcher thinks that this window provides a bridging mechanism to compensate for the fact that ourackf brains are always working on outdated information. Our brains process stimuli that impinged on our senses hundreds of milliseconds ago, but it we were to react with that lag we would not function effectively in the world. Melcher goes on “Our sense of now can be viewed as psychological illusion based on the past and a prediction of the near future, and this illusion is calibrated so that it allows us to do amazing things like run, jump, play sports or drive a car.”

Wittman acknowledges that it is not clear how all this works. The biological of the experienced moment has yet to be found, however neuroscientist Georg Northoff set of the University of Ottawa has proposed one possibility in his 2013 book, Unlocking the Brain. He speculated that implicit timing could be related to slow cortical potentials that provide a kind of background electrical activity measurable across the brain’s cortex. Wittman notes that it’s telling that these waves of electrical activity can last several seconds. He also notes that consciousness itself is kind of filter because it focuses our attention on some things to the exclusion of others. It could be influenced by factors such as emotion or memory, it might tag or label a subset of functional moments as belonging together, to create an experienced moment.

What about meditators who say they are “in the now?” It is clear that it is impossible to be “in the now.” But is it possible that although they appear to be fooling themselves, they are actually accomplish something good? Data indicate that the answer is yes. Wittman did research in which meditators were able to maintain one interpretation of an ambiguous figure longer than non-meditators. Meditators also tend to score higher on tests of attention and working memory capacity. Wittman notes, “If you are more aware of what is happening around you, you not only experience more in the present moment, you also have more memory content.” He also notes, “Meditators perceive time to pass more slowly than non-meditators, both in the present and retrospectively.”

The final paragraph of the New Scientist article merits direct quotation. “This suggests that with a bit of effort we are all capable of manipulating our perception now. If meditation expands your now, then as well as expanding your mind, it could also expand your life. So, grab hold of your consciousness and revel in the moment for longer. There’s no time like the present.”

How Do We See?

October 3, 2010

The study of visual perception is difficult because it happens so fast. Somehow light comes into our eyes, makes contact with our memory and, lo and behold, we see a meaningful scene. A recent article1 in the New Scientist provides an overview of how this occurs, or, at least,with out current state of knowledge how we think this occurs.

Since perception happens so quickly, agnosias, specific disorders, can be quite informative. The previous blog post explored Propagnosia. Other types of agnosias include:

Simultanagnosia – seeing one object at a time when viewing a scene comprised of many items.

Integrative agnosia – Inability to recognize whole objects, tending instead to focus on individual features of an object.

Visual form agnosia – Inability to describe the shape, size, or orientation of objects, but still being able to manipulate them.

Optic ataxia – Ability to report the shape and size of an object, though manipulating the object clumsily.

Pure alexia (aka agnosia for words) – inability to identify individual characters or even text, although sometimes being able to write.

Topographical agnosia – Inability to recognize known landmarks or scenes.

Color agnosia – Ability to perceive colors without being able to identify, name, or group them according to similarity.

Research using brain scans can be quite useful in identifying the specific areas in the brain that accomplish these functions. Brain scans have revealed that people with visual form agnosia tend to have damage to the ventral (lower) part of the brain’s visual area. However, people with optic ataxia tend to have damage to the dorsal (upper part) of the brain’s visual area. So it appears that we have two streams of visual processing. The ventral pathway recognizes the object, while the dorsal pathway determines where that object is located in the visual field.

Some neuroscientists think that the brain binds all the different features of the ventral stream to a “master map of location”, which is held in the dorsal stream. They believe that this binding process is so fundamental that this link needs to be formed before an image can pop into consciousness.

So our perceptual system seems to be highly modular with many different modules contributing to conscious experience. All this activity occurs below the level of consciousness to yield the conscious world we do experience.

1Robeson, D. (2010). Seeing Isn’t Believing. New Scientist, 28 August, 30-33.

© Douglas Griffith and, 2010. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Douglas Griffith and with appropriate and specific direction to the original content.