*This post has moved and can be found at my new (and better) blog here*
Sunday, 21 September 2014
Tuesday, 12 August 2014
Highlighting
Highlighting is one of the most popular learning techniques practiced by students (just look at a second-hand textbook and chances are it will be filled with highlighted or underlined text). It's easy to see why; it requires almost no effort (beyond reading the text itself) and it makes one feel like you are actively learning (e.g. you choose what to highlight). But is there any evidence to support its efficacy?
Unfortunately for students, not really. Cashen & Leitch (1970) found weak evidence that active highlighting aids memory in relation to answering exam questions about the highlighted material. This was replicated in another study by Leitch & Cashen (1972) but the effect was weaker still.
There have been several studies that found highlighting had no effect on subsequent test scores for children (Rickards & Denner, 1979), students with learning disabilities (Nist & Hogrebe, 1987) and typical students (Todd & Kessler, 1971).
Highlighting may even be detrimental to one's learning as students are prone to over-highlighting so the key information is lost in a sea of highlighting and is less distinctive (so therefore is less likely to be remembered, Lorch, Lorch & Klusewitz; 1995). It may also stop students from engaging in genuinely useful learning activities as they feel like they are effectively learning and so do not need to engage in other forms of testing.
The weight of evidence suggests that highlighting has a minimal (at best) effect on learning and in fact may have a detrimental effect overall.
References:
Cashen, V.M. & Leitch, K.L. (1970). Role of the isolation effect in a formal educational setting. Journal of Educational Neuroscience, 61 (6), 484-486.
Dunlosky, J.; Rawson, K.A.; Marsh, E.J.; Nathan, M.J. & Willingham, D.T. (2013). Improving Students' Learning with Effective Learning Techniques: Promising Directions from Cognitive and Educational Psychology. Psychological Science in the Public Interest, 14 (1), 4-58.
Leitch, K.L. & Cashen, V.M. (1972). Type of Highlighted Material and Examination Performance. Journal of Educational Neuroscience, 65 (7), 315-316.
Lorch, R.F.; Lorch, E.P.L. & Klusewitz, M.A. (1995). Effects of Typographical Cues on Reading and Recall of Text. Contemporary Educational Psychology, 20 (1), 51-64.
Nist, S.L. & Hogrebe, M.C. (1987). The Role of Underlining and Annotating in Remembering Textual Information. Reading Research and Instruction, 27 (1), 12-25.
Rickards, J.P. & Denner, P.R. (1979). Depressive effects of underlining and adjunct questions on children's recall of text. Instructional Science, 8 (1), 81-90.
Todd, W.B. & Clemm, C.C. (1971). Influences of response mode, sex, reading ability, and level of difficulty on four measures of recall of meaningful written material. Journal of Educational Psychology, 62 (3), 229-234.
Unfortunately for students, not really. Cashen & Leitch (1970) found weak evidence that active highlighting aids memory in relation to answering exam questions about the highlighted material. This was replicated in another study by Leitch & Cashen (1972) but the effect was weaker still.
There have been several studies that found highlighting had no effect on subsequent test scores for children (Rickards & Denner, 1979), students with learning disabilities (Nist & Hogrebe, 1987) and typical students (Todd & Kessler, 1971).
Highlighting may even be detrimental to one's learning as students are prone to over-highlighting so the key information is lost in a sea of highlighting and is less distinctive (so therefore is less likely to be remembered, Lorch, Lorch & Klusewitz; 1995). It may also stop students from engaging in genuinely useful learning activities as they feel like they are effectively learning and so do not need to engage in other forms of testing.
The weight of evidence suggests that highlighting has a minimal (at best) effect on learning and in fact may have a detrimental effect overall.
References:
Cashen, V.M. & Leitch, K.L. (1970). Role of the isolation effect in a formal educational setting. Journal of Educational Neuroscience, 61 (6), 484-486.
Dunlosky, J.; Rawson, K.A.; Marsh, E.J.; Nathan, M.J. & Willingham, D.T. (2013). Improving Students' Learning with Effective Learning Techniques: Promising Directions from Cognitive and Educational Psychology. Psychological Science in the Public Interest, 14 (1), 4-58.
Leitch, K.L. & Cashen, V.M. (1972). Type of Highlighted Material and Examination Performance. Journal of Educational Neuroscience, 65 (7), 315-316.
Lorch, R.F.; Lorch, E.P.L. & Klusewitz, M.A. (1995). Effects of Typographical Cues on Reading and Recall of Text. Contemporary Educational Psychology, 20 (1), 51-64.
Nist, S.L. & Hogrebe, M.C. (1987). The Role of Underlining and Annotating in Remembering Textual Information. Reading Research and Instruction, 27 (1), 12-25.
Rickards, J.P. & Denner, P.R. (1979). Depressive effects of underlining and adjunct questions on children's recall of text. Instructional Science, 8 (1), 81-90.
Todd, W.B. & Clemm, C.C. (1971). Influences of response mode, sex, reading ability, and level of difficulty on four measures of recall of meaningful written material. Journal of Educational Psychology, 62 (3), 229-234.
Monday, 7 July 2014
A series on... Learning techniques
I'm going to write a series on various learning techniques where I will present the evidence for their efficacy and judge how useful they are for students. The first post will be on active retrieval.
Friday, 30 May 2014
Overcoming stereotype threat
Stereotype threat is the experience of anxiety when you could potentially confirm a negative stereotype about your social group e.g. women are inferior to men at maths, black people are less intelligent than white people. Steele (1997) found that negative stereotypes can negatively impact a person's ability on specific tests (if they belong to the negatively stereotyped group) as they become worried about fulfilling the stereotype and this anxiety impinges their score. But how can this effect be overcome? There have been a variety of methods which have sought to negate this effect, and I will detail some of them here (successful intervention techniques underlined).
Ambady et al. (2004) either primed the participants gender before they answered a set of questions in the study (by flashing words that were linked to being female e.g. "aunt", "girl") or primed them with neutral stimuli. They were then asked to either individuate themselves by listing positive and negative aspects of themselves and provide examples of these personality traits manifesting themselves or answer comparably formatted questions about lions. They found that the gender primed individuated participants performed as well as the non gender primed participants and better than the gender primed non-individuated participants.
Schmiel et al. (2004) made students focus on their (self-rated) most important characteristics e.g. being a musician, athlete etc. They were then exposed to the different conditions. In the intrinsic self-affirmation condition, the participants were asked to say why those aspects of their nature made them feel good regardless of socially imposed standards and performance contingencies e.g. "Being a makes me feel ". Participants in the extrinsic self-esteem condition were made to think about the contingent nature of their most-valued features (the worth of those traits being dependent on other people's judgement) e.g. "When I am a successful I receive ". They found that female participants who affirmed the intrinsic worth of their characteristics performed better than extrinsic self-esteem condition females on a mathematical problem solving task.
Martens et al. (2006) found that female participants who affirmed a valued attribute (by describing how these characteristics were personally important and an instance when they had displayed this trait) performed better than female participants who had not (though the sample of this study was very small).
Good et al. (2008) presented final year calculus students (at a prestigious university) a standardised maths test which was preceded by a paragraph that either emphasised this tests' ability to measure maths proficiency (stereotype threat condition) or one that highlighted that there were no gender differences in score for this test (non-threat condition). They found that female participants in the non-threat condition scored higher than stereotype threat females (they had higher accuracy and answered more questions) and males in both conditions. They found that removing the gender bias before starting a maths test reduced stereotype threat in female participants (though this analysis was only found for Anglo-American participants).
McGlone & Aronson (2006) administering a spatial reasoning test to male and female college students. Prior to this, the researchers presented the participants with one of 3 questionnaires: one that primed gender (by asking questions that made them think about their gender), another that primed the fact they were at a private school (by asking them questions to do with the fact they had earned admittance to a private school), and the third primed the fact they were residents of the Northeastern United States (control group). They found that the the female students who had been primed with the idea they had earned their place at a private school (their "achieved" identities were made salient) performed better than those whose gender had been primed (though this effect wasn't very large).
References:
Ambady, N.; Paik, S.K.; Steele, J.; Owen-Smith, A. & Mitchell, J.P. (2003). Deflecting negative self-relevant stereotype activation: The effects of individuation. Journal of Experimental Social Psychology, 40, 401-408.
Good, C.; Aronson, J. & Harder, J.A. (2008). Problems in the pipeline: Stereotype threat and women's achievement in high-level maths courses. Journal of Applied Developmental Psychology, 29 (1), 17-29.
Martens, A.; Johns, M.; Greenberg, J. & Schimel, J. (2006). Combating stereotype threat: The effect of self-affirmation on women's intellectual performance. Journal of Experimental Social Psychology, 42 (2), 236-243.
McGlone, M.S. & Aronson, J. (2006). Stereotype threat, identity salience, and spatial reasoning. Journal of Applied Developmental Psychology, 27 (5), 486-493.
Schmiel, J.; Arndt, J.; Banko, K.M. & Cook, A. (2004). Not all self-affirmations were created equal: The cognitive and social benefits of affirming the intrinsic (versus extrinsic) self. Social Cognition, 22 (1), 75-99.
Steele, C.M. (1997). A Threat in the Air: How Stereotypes Shape Intellectual Identity and Performance. American Psychologist, 52 (6), 613-629.
Ambady et al. (2004) either primed the participants gender before they answered a set of questions in the study (by flashing words that were linked to being female e.g. "aunt", "girl") or primed them with neutral stimuli. They were then asked to either individuate themselves by listing positive and negative aspects of themselves and provide examples of these personality traits manifesting themselves or answer comparably formatted questions about lions. They found that the gender primed individuated participants performed as well as the non gender primed participants and better than the gender primed non-individuated participants.
Schmiel et al. (2004) made students focus on their (self-rated) most important characteristics e.g. being a musician, athlete etc. They were then exposed to the different conditions. In the intrinsic self-affirmation condition, the participants were asked to say why those aspects of their nature made them feel good regardless of socially imposed standards and performance contingencies e.g. "Being a makes me feel ". Participants in the extrinsic self-esteem condition were made to think about the contingent nature of their most-valued features (the worth of those traits being dependent on other people's judgement) e.g. "When I am a successful I receive ". They found that female participants who affirmed the intrinsic worth of their characteristics performed better than extrinsic self-esteem condition females on a mathematical problem solving task.
Martens et al. (2006) found that female participants who affirmed a valued attribute (by describing how these characteristics were personally important and an instance when they had displayed this trait) performed better than female participants who had not (though the sample of this study was very small).
Good et al. (2008) presented final year calculus students (at a prestigious university) a standardised maths test which was preceded by a paragraph that either emphasised this tests' ability to measure maths proficiency (stereotype threat condition) or one that highlighted that there were no gender differences in score for this test (non-threat condition). They found that female participants in the non-threat condition scored higher than stereotype threat females (they had higher accuracy and answered more questions) and males in both conditions. They found that removing the gender bias before starting a maths test reduced stereotype threat in female participants (though this analysis was only found for Anglo-American participants).
McGlone & Aronson (2006) administering a spatial reasoning test to male and female college students. Prior to this, the researchers presented the participants with one of 3 questionnaires: one that primed gender (by asking questions that made them think about their gender), another that primed the fact they were at a private school (by asking them questions to do with the fact they had earned admittance to a private school), and the third primed the fact they were residents of the Northeastern United States (control group). They found that the the female students who had been primed with the idea they had earned their place at a private school (their "achieved" identities were made salient) performed better than those whose gender had been primed (though this effect wasn't very large).
References:
Ambady, N.; Paik, S.K.; Steele, J.; Owen-Smith, A. & Mitchell, J.P. (2003). Deflecting negative self-relevant stereotype activation: The effects of individuation. Journal of Experimental Social Psychology, 40, 401-408.
Good, C.; Aronson, J. & Harder, J.A. (2008). Problems in the pipeline: Stereotype threat and women's achievement in high-level maths courses. Journal of Applied Developmental Psychology, 29 (1), 17-29.
Martens, A.; Johns, M.; Greenberg, J. & Schimel, J. (2006). Combating stereotype threat: The effect of self-affirmation on women's intellectual performance. Journal of Experimental Social Psychology, 42 (2), 236-243.
McGlone, M.S. & Aronson, J. (2006). Stereotype threat, identity salience, and spatial reasoning. Journal of Applied Developmental Psychology, 27 (5), 486-493.
Schmiel, J.; Arndt, J.; Banko, K.M. & Cook, A. (2004). Not all self-affirmations were created equal: The cognitive and social benefits of affirming the intrinsic (versus extrinsic) self. Social Cognition, 22 (1), 75-99.
Steele, C.M. (1997). A Threat in the Air: How Stereotypes Shape Intellectual Identity and Performance. American Psychologist, 52 (6), 613-629.
Saturday, 3 May 2014
Sunday, 20 April 2014
Monday, 27 January 2014
Myths about the brain no. 7: You can train your brain via games to increase overall intelligence
This is another huge money-making industry based on dubious science. You will probably have seen them advertised ("Luminosity" on various YouTube videos is the one that springs to mind for me) or have at least heard about them. They are generally based on the principle that improving your ability to complete various tasks (usually basic maths problems or spatial navigation tasks) will result in you becoming more intelligent, improving your thinking speed or reasoning ability or any other suitably vague statement. Many of these companies claim to improve working memory, which is a cognitive system that relates to a persons ability to reason with new information and direct your attention towards the goal-relevant information contained in it (Shipstead et al., 2012). It's also been defined as your mental area where you concurrently sort and process information. Working memory has been the focus of many of these companies because of the central role working memory plays in general cognition.
So these companies advertise themselves as being able to help improve your intelligence by improving working memory (via specific tasks, usually a dual n-back test, which is simply where the user has to monitor two streams of info, one visual and one auditory and each time one or both of the streams emits a pre-established target e.g. a bird, then you have to press a button). Now there's no doubt that practicing a task will result in you getting better at it. However, the idea that practicing specific tasks will result in an improvement in a host of other mental faculties has not been shown (as detailed here, here, here and here). There has also been a study detailing why transference doesn't occur. There's also the problem that the study all this research has been based on has some serious methodological flaws in e.g. participants received training on a regular basis (whereas the controls simply went home and did whatever) so the experimental group may have had higher motivation to do well in the study, you can't measure fluid intelligence with one test. Also, when researchers tried to recreate the effect they found no significant effect as a result of training (Redick et al., 2012 and Chooi et al., 2012) which is not good news for the validity of the original study. And to cap it off, a large scale meta-analysis of studies that examined whether training working memory could result in transference of skills found no effect (Melby-Lervag et al., 2013)
So these companies advertise themselves as being able to help improve your intelligence by improving working memory (via specific tasks, usually a dual n-back test, which is simply where the user has to monitor two streams of info, one visual and one auditory and each time one or both of the streams emits a pre-established target e.g. a bird, then you have to press a button). Now there's no doubt that practicing a task will result in you getting better at it. However, the idea that practicing specific tasks will result in an improvement in a host of other mental faculties has not been shown (as detailed here, here, here and here). There has also been a study detailing why transference doesn't occur. There's also the problem that the study all this research has been based on has some serious methodological flaws in e.g. participants received training on a regular basis (whereas the controls simply went home and did whatever) so the experimental group may have had higher motivation to do well in the study, you can't measure fluid intelligence with one test. Also, when researchers tried to recreate the effect they found no significant effect as a result of training (Redick et al., 2012 and Chooi et al., 2012) which is not good news for the validity of the original study. And to cap it off, a large scale meta-analysis of studies that examined whether training working memory could result in transference of skills found no effect (Melby-Lervag et al., 2013)
So whilst it's nice to think you can increase your intelligence by performing a few tasks for a couple of weeks, it seems very unlikely that this is the case.
References:
Berkman, E.T.; Kahn, L.E.; & Merchant, J.S. (2014). Training-Induced Changes in Inhibitory Control Network Activity. The Journal of Neuroscience, 34 (1), 149-157.
Chooi, W.T. & Thompson, L.E. (2012). Working memory training does not improve intelligence in healthy young adults. Intelligence, 40 (6), 531-542.
Jaeggi, S.M.; Buschkuehl, M.; Jonides, J.; & Perrig, W.J. (2008). Improving fluid intelligence with training on working memory. Proceedings of the National Academy of Sciences of the United States of America, 105 (19), 6829-6833.
Melby-Lervag, M. & Hulme, C. (2013). Is working memory training effective? A meta-analytic review. Developmental Psychology, 49 (2), 270-291.
Moody, D.E. (2009). Can intelligence be increased by training on a task of working memory? Intelligence, 37 (4), 327-328.
Redick, T.S.; Shipstead, Z.; Fried, D.E.; Hambrick, D.Z.; Kane, M.J.; & Engle, R.W. (2012). No Evidence of Intelligence Improvement After Working Memory Training: A Randomised, Placebo-Controlled Study. Journal of Experimental Psychology: General, 142 (2), 359-379.
Shipstead, Z.; Hicks, K.L.; & Engle, R.W. (2012). Cogmed working memory training: Does the evidence support the claims? Journal of Applied Research in Memory and Cognition, 1, 185-193.
Shipstead, Z.; Redick, T.S.; & Engle, R.W. (2010). Does Working Memory Training Generalise? Psychologica Belgica, 50 (3-4), 245-276.
Shipstead, Z.; Redick, T.S.; & Engle, R.W. (2012). Is Working Memory Training Effective? Psychological Bulletin, 138 (4), 628-654.
References:
Berkman, E.T.; Kahn, L.E.; & Merchant, J.S. (2014). Training-Induced Changes in Inhibitory Control Network Activity. The Journal of Neuroscience, 34 (1), 149-157.
Chooi, W.T. & Thompson, L.E. (2012). Working memory training does not improve intelligence in healthy young adults. Intelligence, 40 (6), 531-542.
Jaeggi, S.M.; Buschkuehl, M.; Jonides, J.; & Perrig, W.J. (2008). Improving fluid intelligence with training on working memory. Proceedings of the National Academy of Sciences of the United States of America, 105 (19), 6829-6833.
Melby-Lervag, M. & Hulme, C. (2013). Is working memory training effective? A meta-analytic review. Developmental Psychology, 49 (2), 270-291.
Moody, D.E. (2009). Can intelligence be increased by training on a task of working memory? Intelligence, 37 (4), 327-328.
Redick, T.S.; Shipstead, Z.; Fried, D.E.; Hambrick, D.Z.; Kane, M.J.; & Engle, R.W. (2012). No Evidence of Intelligence Improvement After Working Memory Training: A Randomised, Placebo-Controlled Study. Journal of Experimental Psychology: General, 142 (2), 359-379.
Shipstead, Z.; Hicks, K.L.; & Engle, R.W. (2012). Cogmed working memory training: Does the evidence support the claims? Journal of Applied Research in Memory and Cognition, 1, 185-193.
Shipstead, Z.; Redick, T.S.; & Engle, R.W. (2010). Does Working Memory Training Generalise? Psychologica Belgica, 50 (3-4), 245-276.
Shipstead, Z.; Redick, T.S.; & Engle, R.W. (2012). Is Working Memory Training Effective? Psychological Bulletin, 138 (4), 628-654.
Friday, 24 January 2014
Myths about the brain no. 6: Listening to Mozart will make you smarter.
The idea of increasing your
IQ by doing the simple act of listening to the music of Wolfgang Amadeus Mozart
has been around since the 1950’s and has grown into a full blow industry, with
endless books, CD’s and DVD’s. Despite it being highly lucrative and popular,
there’s absolutely no evidence to suggest it is true (surprise surprise).
The scientific genesis of this myth comes from a study in the 1990’s, which found that subjects who had listened to 10 minutes of a Mozart sonata scored higher than those who didn’t. (The study had a very small number of participants and was between subjects, so they can’t even be certain the higher reported scores weren’t due to the “Mozart hearing” group just being more intelligent). This story was taken by the media and blown up to create the idea that listening to Mozart will make you smarter over the long-term. However, the initial study didn’t even test overall intelligence, it only tested participants on a few spatial-temporal tasks, and the effect wore off after 15 minutes. There’s also the small problem that the effect hasn’t been replicated under more controlled conditions (a key tenet of science is being able to replicate an effect under the same or similar circumstances). Several follow-up studies have found that listening to Mozart can temporarily increase cognitive skills whilst many more studies found no significant effect.
So it seems extremely unlikely that listening to Mozart will result in any long-term increase in your cognitive faculties. Learning to play an instrument however, has been shown to improve vocabulary, reading performance and a whole host of other skills.
References:
Hallam, S. (2010). The power of music: It's impact on the intellectual, social, and personal development of children and young people. International Journal of Music Education, 28, 3, 269-289.
Lamb, S.J. & Gregory, A.H. (1993). The Relationship between Music and Reading in Beginning Readers. Educational Psychology: An International Journal of Experimental Educational Psychology, 13, 1, 19-27.
Piro, J.M. & Ortiz, C. (2009). The effect of piano lessons on the vocabulary and verbal sequencing skills primary grade students. Psychology of Music, doi: 10.1177/0305735608097248
The scientific genesis of this myth comes from a study in the 1990’s, which found that subjects who had listened to 10 minutes of a Mozart sonata scored higher than those who didn’t. (The study had a very small number of participants and was between subjects, so they can’t even be certain the higher reported scores weren’t due to the “Mozart hearing” group just being more intelligent). This story was taken by the media and blown up to create the idea that listening to Mozart will make you smarter over the long-term. However, the initial study didn’t even test overall intelligence, it only tested participants on a few spatial-temporal tasks, and the effect wore off after 15 minutes. There’s also the small problem that the effect hasn’t been replicated under more controlled conditions (a key tenet of science is being able to replicate an effect under the same or similar circumstances). Several follow-up studies have found that listening to Mozart can temporarily increase cognitive skills whilst many more studies found no significant effect.
So it seems extremely unlikely that listening to Mozart will result in any long-term increase in your cognitive faculties. Learning to play an instrument however, has been shown to improve vocabulary, reading performance and a whole host of other skills.
References:
Hallam, S. (2010). The power of music: It's impact on the intellectual, social, and personal development of children and young people. International Journal of Music Education, 28, 3, 269-289.
Lamb, S.J. & Gregory, A.H. (1993). The Relationship between Music and Reading in Beginning Readers. Educational Psychology: An International Journal of Experimental Educational Psychology, 13, 1, 19-27.
Piro, J.M. & Ortiz, C. (2009). The effect of piano lessons on the vocabulary and verbal sequencing skills primary grade students. Psychology of Music, doi: 10.1177/0305735608097248
Myths about the brain no. 5: Drug use creates holes in the brain
This article isn’t looking at what effects different drugs
have on the brain (though I’ll discuss that in another article as it’s a
controversial topic) but about the myth that any form of drug use will create physical
holes in your brain.
Different drugs have different effects (obviously…) and
abusing them can cause serious damage to yourself (they can interfere with your
neural pathways, cause addiction etc). One of the main ways it does this is by
interfering with the neurons in your brain by binding to neuron receptors. They
can then mimic the effect of different neurotransmitters (chemical messengers)
and make these receptors under- or over-sensitive to neurotransmitters and this
has a major impact on your brain and how it functions. (For more detail on this
process, check out this Scientific American article). They can also change the
structure of your brain, depending on what drug you abuse. But what they do not
do is create actual holes in your brain. The only thing that can create holes
is physical trauma.
Sources:
http://science.howstuffworks.com/life/inside-the-mind/human-brain/10-brain-myths.htm#page=2
Sources:
http://science.howstuffworks.com/life/inside-the-mind/human-brain/10-brain-myths.htm#page=2
Saturday, 18 January 2014
Myths about the brain no. 4: A person's memory of an event is very accurate
The idea that some people have better memories than others isn't a new or groundbreaking idea. But most people will feel they have a good memory with regards to events that have just happened or with events that have a personal meaning e.g. one of your birthday parties. This idea is the implicit assumption behind eye-witness testimonies; people will accurately remember what happened at a specific time and be able to give an accurate account of it.
However, there has been evidence to suggest this is not the case. People generally do not remember specific details well; they remember the critical ideas of what occurred or random specific memories, and make up the rest (if they are required to recall it). Dan Gilbert talks about this extensively in his book Stumbling on Happiness. Memories are not only constructive, they are reconstructive. They can be changed after the event has occurred, and not necessarily by you.
The idea of memories being altered by outside influence goes back to the 1970's with a study by Elizabeth Loftus and John Palmer (1974). They found that how the question was phrased (specifically, whether word "hit" or "smashed" was used) affected people's estimations about how fast two cars were travelling (on average, people in the "smashed" condition thought the cars were travelling 6mph faster than in the "hit" condition) and whether they would later report seeing broken glass (there was none).
So our memories can be influenced by external factors. What about internal ones? Stress has been shown repeatedly to affect delayed retrieval of a memory (e.g. Kuhlmann et al., 2005) and this has worrying implications for the validity of eye witness testimonies. Eye witness testimonies are generally seen as very powerful evidence but given how unreliable memory can be, you have to question whether it should carry so much weight. There is even a foundation set up to help those who have been incorrectly incarcerated (The Innocence Project) and about 3/4's of the convictions were based on (what were later shown to be) false memories.
Emotions are generally believed to influence memory as well, with people believing that they remember something better if it is associated with a powerful emotion. However, there is no evidence to suggest this is the case (Kensinger, 2007) and people overestimate their ability to recall emotionally charged memories.
It's not all doom and gloom though. I've painted a picture of human memory being almost worthless, when in fact it is very powerful and generally pretty good (though there are ways of improving it). But we shouldn't view our memories as infallible and we should recognise that we can incorrectly code an event into our memory or that our memory can be altered once it has been stored in our long-term memory.
However, there has been evidence to suggest this is not the case. People generally do not remember specific details well; they remember the critical ideas of what occurred or random specific memories, and make up the rest (if they are required to recall it). Dan Gilbert talks about this extensively in his book Stumbling on Happiness. Memories are not only constructive, they are reconstructive. They can be changed after the event has occurred, and not necessarily by you.
The idea of memories being altered by outside influence goes back to the 1970's with a study by Elizabeth Loftus and John Palmer (1974). They found that how the question was phrased (specifically, whether word "hit" or "smashed" was used) affected people's estimations about how fast two cars were travelling (on average, people in the "smashed" condition thought the cars were travelling 6mph faster than in the "hit" condition) and whether they would later report seeing broken glass (there was none).
So our memories can be influenced by external factors. What about internal ones? Stress has been shown repeatedly to affect delayed retrieval of a memory (e.g. Kuhlmann et al., 2005) and this has worrying implications for the validity of eye witness testimonies. Eye witness testimonies are generally seen as very powerful evidence but given how unreliable memory can be, you have to question whether it should carry so much weight. There is even a foundation set up to help those who have been incorrectly incarcerated (The Innocence Project) and about 3/4's of the convictions were based on (what were later shown to be) false memories.
Emotions are generally believed to influence memory as well, with people believing that they remember something better if it is associated with a powerful emotion. However, there is no evidence to suggest this is the case (Kensinger, 2007) and people overestimate their ability to recall emotionally charged memories.
It's not all doom and gloom though. I've painted a picture of human memory being almost worthless, when in fact it is very powerful and generally pretty good (though there are ways of improving it). But we shouldn't view our memories as infallible and we should recognise that we can incorrectly code an event into our memory or that our memory can be altered once it has been stored in our long-term memory.
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