visual memory

Gist memory may be why false memories are more common in older adults

  • Gist processing appears to play a strong role in false memories.
  • Older adults rely on gist memory more.
  • Older adults find it harder to recall specific sensory details that would help confirm whether a memory is true.

Do older adults forget as much as they think, or is it rather that they ‘misremember’?

A small study adds to evidence that gist memory plays an important role in false memories at any age, but older adults are more susceptible to misremembering because of their greater use of gist memory.

Gist memory is about remembering the broad story, not the details. We use schemas a lot. Schemas are concepts we build over time for events and experiences, in order to relieve the cognitive load. They allow us to respond and process faster. We build schemas for such things as going to the dentist, going to a restaurant, attending a lecture, and so on. Schemas are very useful, reminding us what to expect and what to do in situations we have experienced before. But they are also responsible for errors of perception and memory — we see and remember what we expect to see.

As we get older, we do of course build up more and firmer schemas, making it harder to really see with fresh eyes. Which means it’s harder for us to notice the details, and easier for us to misremember what we saw.

A small study involving 20 older adults (mean age 75) had participants look at 26 different pictures of common scenes (such as a farmyard, a bathroom) for about 10 seconds, and asked them to remember as much as they could about the scenes. Later, they were shown 300 pictures of objects that were either in the scene, related to the scene (but not actually in the scene), or not commonly associated to the scene, and were required to say whether or not the objects were in the picture. Brain activity was monitored during these tests. Performance was also compared with that produced in a previous identical study, involving 22 young adults (mean age 23).

As expected and as is typical, there was a higher hit rate for schematic items and a higher rate of false memories for schematically related lures (items that belong to the schema but didn’t appear in the picture). True memories activated the typical retrieval network (medial prefrontal cortex, hippocampus/parahippocampal gyrus, inferior parietal lobe, right middle temporal gyrus, and left fusiform gyrus).

Activity in some of these regions (frontal-parietal regions, left hippocampus, right MTG, and left fusiform) distinguished hits from false alarms, supporting the idea that it’s more demanding to retrieve true memories than illusory ones. This contrasts with younger adults who in this and previous research have displayed the opposite pattern. The finding is consistent, however, with the theory that older adults tend to engage frontal resources at an earlier level of difficulty.

Older adults also displayed greater activation in the medial prefrontal cortex for both schematic and non-schematic hits than young adults did.

While true memories activated the typical retrieval network, and there were different patterns of activity for schematic vs non-schematic hits, there was no distinctive pattern of activity for retrieving false memories. However, there was increased activity in the middle frontal gyrus, middle temporal gyrus, and hippocampus/parahippocampal gyrus as a function of the rate of false memories.

Imaging also revealed that, like younger adults, older adults also engage the ventromedial prefrontal cortex when retrieving schematic information, and that they do so to a greater extent. Activation patterns also support the role of the mediotemporal lobe (MTL), and the posterior hippocampus/parahippocampal gyrus in particular, in determining true memories from false. Note that schematic information is not part of this region’s concern, and there was no consistent difference in activation in this region for schematic vs non-schematic hits. But older adults showed this shift within the hippocampus, with much of the activity moving to a more posterior region.

Sensory details are also important for distinguishing between true and false memories, but, apart from activity in the left fusiform gyrus, older adults — unlike younger adults — did not show any differential activation in the occipital cortex. This finding is consistent with previous research, and supports the conclusion that older adults don’t experience the recapitulation of sensory details in the same way that younger adults do. This, of course, adds to the difficulty they have in distinguishing true and false memories.

Older adults also showed differential activation of the right MTG, involved in gist processing, for true memories. Again, this is not found in younger adults, and supports the idea that older adults depend more on schematic gist information to assess whether a memory is true.

However, in older adults, increased activation of both the MTL and the MTG is seen as rates of false alarms increase, indicating that both gist and episodic memory contribute to their false memories. This is also in line with previous research, suggesting that memories of specific events and details can (incorrectly) provide support for false memories that are consistent with such events.

Older adults, unlike young adults, failed to show differential activity in the retrieval network for targets and lures (items that fit in with the schema, but were not in fact present in the image).

What does all this mean? Here’s what’s important:

  • older adults tend to use schema information more when trying to remember
  • older adults find it harder to recall specific sensory details that would help confirm a memory’s veracity
  • at all ages, gist processing appears to play a strong role in false memories
  • memory of specific (true) details can be used to endorse related (but false) details.

What can you do about any of this? One approach would be to make an effort to recall specific sensory details of an event rather than relying on the easier generic event that comes to mind first. So, for example, if you’re asked to go to the store to pick up orange juice, tomatoes and muesli, you might end up with more familiar items — a sort of default position, as it were, because you can’t quite remember what you were asked. If you make an effort to remember the occasion of being told — where you were, how the other person looked, what time of day it was, other things you talked about, etc — you might be able to bring the actual items to mind. A lot of the time, we simply don’t make the effort, because we don’t think we can remember.

https://www.eurekalert.org/pub_releases/2018-03/ps-fdg032118.php

Reference: 

Topics: 

tags problems: 

tags development: 

tags memworks: 

Eye movements get re-enacted when we remember

  • An imaging and eye-tracking study has shown that the brain uses eye movements to help us recall remembered images.

A small study has tested the eminent Donald Hebb’s hypothesis that visual imagery results from the reactivation of neural activity associated with viewing images, and that the re-enactment of eye-movement patterns helps both imagery and neural reactivation.

In the study, 16 young adults (aged 20-28) were shown a set of 14 distinct images for a few seconds each. They were asked to remember as many details of the picture as possible so they could visualize it later on. They were then cued to mentally visualize the images within an empty rectangular box shown on the screen.

Brain imaging and eye-tracking technology revealed that the same pattern of eye movements and brain activation occurred when the image was learned and when it was recalled. During recall, however, the patterns were compressed (which is consistent with our experience of remembering, where memories take a much shorter time than the original experiences).

Our understanding of memory is that it’s constructive — when we remember, we reconstruct the memory from separate bits of information in our database. This finding suggests that eye movements might be like a blueprint to help the brain piece together the bits in the right way.

https://www.eurekalert.org/pub_releases/2018-02/bcfg-cga021318.php

Reference: 

tags memworks: 

Topics: 

Muscular strength linked to brain health & cognitive function

  • A study of nearly half a million people has revealed that muscular strength is associated with brain health and cognitive performance, including among schizophrenics.

A British study using data from 475,397 participants has shown that, on average, stronger people performed better across every test of brain functioning used. Tests looked at reaction speed, reasoning, visuospatial memory, prospective memory, and working memory (digit span). The relationship between muscular strength and brain function was consistently strong in both older and younger adults (those under 55 and those over), contradicting previous research showing it only in older adults.

The study also found that maximal handgrip was strongly correlated with both visuospatial memory and reaction time in 1,162 people with schizophrenia (prospective memory also approached statistical significance).

The finding raises the intriguing possibility that weight training could be particularly beneficial for people with mental health conditions, such as schizophrenia, major depression and bipolar disorder.

https://www.eurekalert.org/pub_releases/2018-04/nwsu-rrs041918.php

Full text available online at https://doi.org/10.1093/schbul/sby034

Reference: 

Source: 

tags lifestyle: 

Topics: 

tags memworks: 

Drawing best encoding strategy

  • Even quick and not particularly skilled sketches make simple information significantly more likely to be remembered, probably because drawing incorporates several factors that are known to improve memorability.

In a series of experiments involving college students, drawing pictures was found to be the best strategy for remembering lists of words.

The basic experiment involved students being given a list of simple, easily drawn words, for each of which they had 40 seconds to either draw the word, or write it out repeatedly. Following a filler task (classifying musical tones), they were given 60 seconds to then recall as many words as possible. Variations of the experiment had students draw the words repeatedly, list physical characteristics, create mental images, view pictures of the objects, or add visual details to the written letters (such as shading or other doodles).

In all variations, there was a positive drawing effect, with participants often recalling more than twice as many drawn than written words.

Importantly, the quality of the drawings didn’t seem to matter, nor did the time given, with even a very brief 4 seconds being enough. This challenges the usual explanation for drawing benefits: that it simply reflects the greater time spent with the material.

Participants were rated on their ability to form vivid mental images (measured using the VVIQ), and questioned about their drawing history. Neither of these factors had any reliable effect.

The experimental comparisons challenge various theories about why drawing is beneficial:

  • that it processes the information more deeply (when participants in the written word condition listed semantic characteristics of the word, thus processing it more deeply, the results were no better than simply writing out the word repeatedly, and drawing was still significantly better)
  • that it evokes mental imagery (when some students were told to mentally visualize the object, their recall was intermediate between the write and draw conditions)
  • that it simply reflects the fact that pictures are remembered better (when some students were shown a picture of the target word during the encoding time, their recall performance was not significantly better than that of the students writing the words)

The researchers suggest that it is a combination of factors that work together to produce a greater effect than the sum of each. These factors include mental imagery, elaboration, the motor action, and the creation of a picture. Drawing brings all these factors together to create a stronger and more integrated memory code.

http://www.eurekalert.org/pub_releases/2016-04/uow-ntr042116.php

Reference: 

[4245] Wammes JD, Meade ME, Fernandes MA. The drawing effect: Evidence for reliable and robust memory benefits in free recall. The Quarterly Journal of Experimental Psychology [Internet]. 2016 ;69(9):1752 - 1776. Available from: http://dx.doi.org/10.1080/17470218.2015.1094494

Source: 

tags memworks: 

tags study: 

Topics: 

tags strategies: 

Exercise might help your vision

  • A small study found that low-intensity exercise significantly boosted activation in the visual cortex above what occurred during rest or high-intensity exercise.

A study involving 18 volunteers who performed a simple orientation discrimination while on a stationary bicycle, has found that low-intensity exercise boosted activation in the visual cortex, compared with activation levels when at rest or during high-intensity exercise.

The changes suggest that the neurons in the visual cortex were most sensitive to the orientation stimuli during the low-intensity exercise condition relative to the other conditions. It’s suggested that this reflects an evolutionary pressure for the visual system to be more sensitive when the individual is actively exploring the environment (as opposed to, say, running away).

http://www.futurity.org/vision-exercise-brains-1400422-2/

Reference: 

Source: 

tags lifestyle: 

Topics: 

tags memworks: 

Being overweight linked to poorer memory

  • A study of younger adults adds to evidence that higher BMI is associated with poorer cognition, and points to a specific impairment in memory integration.

A small study involving 50 younger adults (18-35; average age 24) has found that those with a higher BMI performed significantly worse on a computerised memory test called the “Treasure Hunt Task”.

The task involved moving food items around complex scenes (e.g., a desert with palm trees), hiding them in various locations, and indicating afterward where and when they had hidden them. The test was designed to disentangle object, location, and temporal order memory, and the ability to integrate those separate bits of information.

Those with higher BMI were poorer at all aspects of this task. There was no difference, however, in reaction times, or time taken at encoding. In other words, they weren't slower, or less careful when they were learning. Analysis of the errors made indicated that the problem was not with spatial memory, but rather with the binding of the various elements into one coherent memory.

The results could suggest that overweight people are less able to vividly relive details of past events. This in turn might make it harder for them to keep track of what they'd eaten, perhaps making overeating more likely.

The 50 participants included 27 with BMI below 25, 24 with BMI 25-30 (overweight), and 8 with BMI over 30 (obese). 72% were female. None were diagnosed diabetics. However, the researchers didn't take other health conditions which often co-occur with obesity, such as hypertension and sleep apnea, into account.

This is a preliminary study only, and further research is needed to validate its findings. However, it's significant in that it adds to growing evidence that the cognitive impairments that accompany obesity are present early in adult life and are not driven by diabetes.

The finding is also consistent with previous research linking obesity with dysfunction of the hippocampus and the frontal lobe.

http://www.eurekalert.org/pub_releases/2016-02/uoc-bol022616.php

https://www.theguardian.com/science/neurophilosophy/2016/mar/03/obesity-linked-to-memory-deficits

Reference: 

[4183] Cheke LG, Simons JS, Clayton NS. Higher body mass index is associated with episodic memory deficits in young adults. The Quarterly Journal of Experimental Psychology [Internet]. 2015 :1 - 12. Available from: http://dx.doi.org/10.1080/17470218.2015.1099163

Source: 

tags lifestyle: 

tags problems: 

Topics: 

tags memworks: 

Physical activity linked to better memory for names and faces among older adults

  • A small study adds to evidence that walking improves memory in older adults, and indicates that this is particularly helpful for memory tasks the seniors find challenging.

A small study that fitted 29 young adults (18-31) and 31 older adults (55-82) with a device that recorded steps taken and the vigor and speed with which they were made, has found that those older adults with a higher step rate performed better on memory tasks than those who were more sedentary. There was no such effect seen among the younger adults.

Improved memory was found for both visual and episodic memory, and was strongest with the episodic memory task. This required recalling which name went with a person's face — an everyday task that older adults often have difficulty with.

However, the effect on visual memory had more to do with time spent sedentary than step rate. With the face-name task, both time spent sedentary and step rate were significant factors, and both factors had a greater effect than they had on visual memory.

Depression and hypertension were both adjusted for in the analysis.

There was no significant difference in executive function related to physical activity, although previous studies have found an effect. Less surprisingly, there was also no significant effect on verbal memory.

Both findings might be explained in terms of cognitive demand. The evidence suggests that the effect of physical exercise is only seen when the task is sufficiently cognitively demanding. No surprise that verbal memory (which tends to be much less affected by age) didn't meet that challenge, but interestingly, the older adults in this study were also less impaired on executive function than on visual memory. This is unusual, and reminds us that, especially with small studies, you cannot ignore the individual differences.

This general principle may also account for the lack of effect among younger adults. It is interesting to speculate whether physical activity effects would be found if the younger adults were given much more challenging tasks (either by increasing their difficulty, or selecting a group who were less capable).

Step Rate was calculated by total steps taken divided by the total minutes in light, moderate, and vigorous activities, based on the notion that this would provide an independent indicator of physical activity intensity (how briskly one is walking). Sedentary Time was the total minutes spent sedentary.

http://www.eurekalert.org/pub_releases/2015-11/bumc-slp112415.php

Reference: 

[4045] Hayes SM, Alosco ML, Hayes JP, Cadden M, Peterson KM, Allsup K, Forman DE, Sperling RA, Verfaellie M. Physical Activity Is Positively Associated with Episodic Memory in Aging. Journal of the International Neuropsychological Society [Internet]. 2015 ;21(Special Issue 10):780 - 790. Available from: http://journals.cambridge.org/article_S1355617715000910

Source: 

tags development: 

tags memworks: 

Topics: 

tags lifestyle: 

Clarity in short-term memory shows no link with IQ

December, 2010

The two measures of working memory capacity appear to be fully independent, and only one of them is related to intelligence.

The number of items a person can hold in short-term memory is strongly correlated with their IQ. But short-term memory has been recently found to vary along another dimension as well: some people remember (‘see’) the items in short-term memory more clearly and precisely than other people. This discovery has lead to the hypothesis that both of these factors should be considered when measuring working memory capacity. But do both these aspects correlate with fluid intelligence?

A new study presented 79 students with screen displays fleetingly showing either four or eight items. After a one-second blank screen, one item was returned and the subject asked whether that object had been in a particular location previously. Their ability to detect large and small changes in the items provided an estimate of how many items the individual could hold in working memory, and how clearly they remembered them. These measures were compared with individuals’ performance on standard measures of fluid intelligence.

Analysis of data found that these two measures of working memory — number and clarity —are completely independent of each other, and that it was the number factor only that correlated with intelligence.

This is not to say that clarity is unimportant! Only that it is not related to intelligence.

Reference: 

Source: 

tags memworks: 

Topics: 

Cognition impaired by low-level exposure to organophosphate pesticides

January, 2013

A meta-analysis has concluded that low-level exposure to organophosphates has a small-to-moderate negative effect on cognitive function.

Organophosphate pesticides are the most widely used insecticides in the world; they are also (according to WHO), one of the most hazardous pesticides to vertebrate animals. While the toxic effects of high levels of organophosphates are well established, the effects of long-term low-level exposure are still controversial.

A meta-analysis involving 14 studies and more than 1,600 participants, reveals that the majority of well-designed studies undertaken over the last 20 years have found a significant association between low-level exposure to organophosphates and impaired cognitive function. Impairment was small to moderate, and mainly concerned psychomotor speed, executive function, visuospatial ability, working memory, and visual memory.

Reference: 

Source: 

tags: 

Topics: 

tags memworks: 

tags lifestyle: 

Spatial skills can be improved through training

October, 2012

A review has concluded that spatial training produces significant improvement, particularly for poorer performers, and that such training could significantly increase STEM achievement.

Spatial abilities have been shown to be important for achievement in STEM subjects (science, technology, engineering, math), but many people have felt that spatial skills are something you’re either born with or not.

In a comprehensive review of 217 research studies on educational interventions to improve spatial thinking, researchers concluded that you can indeed improve spatial skills, and that such training can transfer to new tasks. Moreover, not only can the right sort of training improve spatial skill in general, and across age and gender, but the effect of training appears to be stable and long-lasting.

One interesting finding (the researchers themselves considered it perhaps the most important finding) was the diversity in effective training — several different forms of training can be effective in improving spatial abilities. This may have something to do with the breadth covered by the label ‘spatial ability’, which include such skills as:

  • Perceiving objects, paths, or spatial configurations against a background of distracting information;
  • Piecing together objects into more complex configurations, visualizing and mentally transforming objects;
  • Understanding abstract principles, such as horizontal invariance;
  • Visualizing an environment in its entirety from a different position.

The review compared three types of training. Those that used:

  • Video games (24 studies)
  • Semester-long instructional courses on spatial reasoning (42 studies)
  • Practical training, often in a lab, that involved practicing spatial tasks, strategic instruction, or computerized lessons (138 studies).

The first two are examples of indirect training, while the last involves direct training.

On average, taken across the board, training improved performance by well over half a standard deviation when considered on its own, and still almost one half of a standard deviation when compared to a control group. This is a moderately large effect, and it extended to transfer tasks.

It also conceals a wide range, most of which is due to different treatment of control groups. Because the retesting effect is so strong in this domain (if you give any group a spatial test twice, regardless of whether they’ve been training in between the two tests, they’re going to do better on the second test), repeated testing can have a potent effect on the control group. Some ‘filler’ tasks can also inadvertently improve the control group’s performance. All of this will reduce the apparent effect of training. (Not having a control group is even worse, because you don’t know how much of the improvement is due to training and how much to the retesting effect.)

This caution is, of course, more support for the value of practice in developing spatial skills. This is further reinforced by studies that were omitted from the analysis because they would skew the data. Twelve studies found very high effect sizes — more than three times the average size of the remaining studies. All these studies took place in poorly developed countries (those with a Human Development Index above 30 at the time of the study) — Malaysia, Turkey, China, India, and Nigeria. HDI rating was even associated with the benefits of training in a dose-dependent manner — that is, the lower the standard of living, the greater the benefit.

This finding is consistent with other research indicating that lower socioeconomic status is associated with larger responses to training or intervention.

In similar vein, when the review compared 19 studies that specifically selected participants who scored poorly on spatial tests against the other studies, they found that the effects of training were significantly bigger among the selected studies.

In other words, those with poorer spatial skills will benefit most from training. It may be, indeed, that they are poor performers precisely because they have had little practice at these tasks — a question that has been much debated (particularly in the context of gender differences).

It’s worth noting that there was little difference in performance on tests carried out immediately after training ended, within a week, or within a month, indicating promising stability.

A comparison of different types of training did find that some skills were more resistant to training than others, but all types of spatial skill improved. The differences may be because some sorts of skill are harder to teach, and/or because some skills are already more practiced than others.

Given the demonstrated difficulty in increasing working memory capacity through training, it is intriguing to notice one example the researchers cite: experienced video game players have been shown to perform markedly better on some tasks that rely on spatial working memory, such as a task requiring you to estimate the number of dots shown in a brief presentation. Most of us can instantly recognize (‘subitize’) up to five dots without needing to count them, but video game players can typically subitize some 7 or 8. The extent to which this generalizes to a capacity to hold more elements in working memory is one that needs to be explored. Video game players also apparently have a smaller attentional blink, meaning that they can take in more information.

A more specific practical example of training they give is that of a study in which high school physics students were given training in using two- and three-dimensional representations over two class periods. This training significantly improved students’ ability to read a topographical map.

The researchers suggest that the size of training effect could produce a doubling of the number of people with spatial abilities equal to or greater than that of engineers, and that such training might lower the dropout rate among those majoring in STEM subjects.

Apart from that, I would argue many of us who are ‘spatially-challenged’ could benefit from a little training!

Reference: 

Source: 

tags lifestyle: 

Topics: 

tags strategies: 

tags memworks: 

Pages

Subscribe to RSS - visual memory