Archive

Archive for the ‘learning’ Category

Learning and Recall – Hippocampal Firing

September 5th, 2008 1 comment

Today in Science a team of scientists (Hagar Gelbard-Sagiv, Roy Mukamel, Michal Harel, Rafael Malach, and  Itzhak Fried) at the Weizmann Institute of Science in Israel, UCLA, and Tel Aviv University published their research where they directly recorded via implanted electrodes the firing of hippocampus neurons during learning and free recall. This represents the first time in humans this has been done. Here’s the abstract from Science:

The emergence of memory, a trace of things past, into human consciousness is one of the greatest mysteries of the human mind. Whereas the neuronal basis of recognition memory can be probed experimentally in human and nonhuman primates, the study of free recall requires that the mind declare the occurrence of a recalled memory (an event intrinsic to the organism and invisible to an observer). Here, we report the activity of single neurons in the human hippocampus and surrounding areas when subjects first view television episodes consisting of audiovisual sequences and again later when they freely recall these episodes. A subset of these neurons exhibited selective firing, which often persisted throughout and following specific episodes for as long as 12 seconds. Verbal reports of memories of these specific episodes at the time of free recall were preceded by selective reactivation of the same hippocampal and entorhinal cortex neurons. We suggest that this reactivation is an internally generated neuronal correlate of the subjective experience of spontaneous emergence of human recollection. (Published Online September 4, 2008; Science DOI: 10.1126/science.1164685)

The New York Times also has an article about the research.

The Psychology of Multiple-Choice Tests

February 29th, 2008 1 comment

As someone with many years of taking multiple-choice tests as well as a fair amount of experience writing them, I thought it was time to talk about the psychology behind them as well as offer tips to successfully taking them. I’ve personally never enjoyed essay tests (although I know that they separate out those who really know the material from those who do not) – I see their uses and recognize (obscure pun not intended) their strengths but I’m just not a fan in general. Maybe it’s partly because I’m much better at multiple-choice tests and partly because I’m not the fastest writer. I’m usually one of the first done with a multiple-choice test and one of the last with an essay test.

When looking at declarative memory (e.g., memory for facts) there are both recall and recognition components. Recall memory is like taking an essay test – you just have to write whatever you can about a topic. Recognition memory is like taking a multiple-choice test – the answer is in front of you (even if the answer is none of the above). The questions and answers serve as cues that can stimulate your memory. If you have good recall you should have good recognition; if you have poor recall you might still have good recognition (you can also have poor recall and recognition).

Why do some people just not like multiple-choice tests? I’ve heard everything from, “The questions are often tricky” to “I’m just not good at them.” Yes, multiple-choice tests can be tricky but good ones are not necessarily tricky. I say necessarily because what’s tricky to one can be seen as an important distinction by another. Good multiple-choice tests are also organized how class material was organized – that is, topics or chapters all lumped together. I know many people disagree with that point but the test questions and not the test structure should serve to distinguish between people who really understand the material and those who do not. In other words, the structure of the test should serve to facilitate memory by grouping topics and chapters together. Tests should also be given in the context in which material was learned for best results.

When I’ve written tests (as in creating them, not taking them {in case any Canadians read this}) I also tried to make questions test latent knowledge about concepts rather than manifest memory, if I can use structural equations modeling terms. For example, I wrote a question once that sought to pull out knowledge about where modern intelligence tests were developed (i.e., in France). So to test this instead of just asking what country they were developed in, I asked what was a possible name of someone who would have taken one of the early tests (a French name was the correct answer). While doing this has its own problems and limitations, it requires students to think, “OK, they were developed in France so I need a French name” or, “Binet developed the modern IQ test, Binet was French, so I need a French name.” Testing in this manner is an indirect way to get to the core knowledge. That was a fairly straightforward and simple example but testing in that manner (i.e., indirectly) overcomes some of the shortcomings of multiple-choice tests – it requires some reasoning and abstraction. All my test questions were not like that but that is a very effective way to test. I believe it’s also important to teach while testing. Sometimes this entails expanding a question to include a general statement about a topic, then asking something specific. For example, “William James was a 19th century philosopher who is often credited with being the ‘Father of Modern Psychology.’ William James believed all of the following about consciousness EXCEPT:….” Providing an extra sentence not only teaches but also serves as a cue. It should never be a distractor though (unless the question warrants it – for example, on a question about cognitive inhibition or the frontal lobes, then a distractor sentence could be included for astute students to catch the principle of it and be taught, or at least appreciate it). Tests should be constructed to teach. For me, making tests is an art. They should be crafted to help students, facilitate learning, as well as separate the wheat from the chaff. I’m also a firm believer in using humor on tests. The occasional distractor answer should be humorous or blatantly untrue (of course, it’s always funny when someone endorses one of the obviously untrue answers).

My test-making philosophy (and psychology) is based on differentiating the poor from the mediocre students and the mediocre from the good and the good from the great. This is a philosophy that students do not particularly like because it means that I try to write difficult tests. Difficult is not tricky or nit-picky (although it is good to have a couple nit-picky questions), difficult is well-written, requiring reasoning and deeper thinking. When writing tests I try to avoid both ceiling and floor effects. Getting all the questions correct is possible but rare (i.e., no more than 1-3 students in a class of 50 should get 100%). I try to write my tests to have an average score in the mid 70s. Having an average in the mid 70s basically guarantees that there are no floor or ceiling effects and that the test is not too difficult that it is frustrating to too many people. I’m also a big believer in mercy so I like to curve grades (I only curve up, not down). I also usually provide students an opportunity to go back over their tests, correct what they missed and resubmit the tests so they can earn back 25% of the points that they missed. This helps students on the lower end more than on the higher end, but the ones on the high end don’t need higher grades.Do It Yourself Frontal Lobotomy

So now to test-taking strategies. Here are my Top 11 Multiple-Choice Test-Taking Strategies:

  1. Work through the test as quickly as possible answering the questions that you can answer right away. It’s okay to think about one for a little bit but if you can’t get it within a little bit, move on. On longer tests, there are often questions or answers that will help you answer some of the questions you didn’t know.
  2. It’s also okay to work from the end to the beginning or to skip around. Don’t skip around too much though, especially in tests structured by topic or chapter.
  3. Always go with your first impression about an answer unless you are sure that you need to change your answer or if your first impression was just a guess. There is conflicting evidence as to whether or not first impressions are more accurate but in my experience they are.
  4. Look for patterns in answers. For example: A) James, Freud, and Watson; B) Thorndike, Skinner, and Watson; C) Thorndike, Piaget, and Ebbinghaus; D) Skinner, Thorndike, and Beck. In this case the answer is B) (assuming the question is something like which group of psychologists are all behaviorists?). Notice that Watson is repeated twice, Thorndike is repeated 3 times, and Skinner is repeated twice. If you knew nothing about the question you could use logic to figure it out. This does not always work but it often does.
  5. Related the point 4, always try to rule out any answers that you know are not true. Then if you have to guess, you have better odds. This works one tests that penalize you for wrong answers (like many standardized tests do). If a multiple-choice test is designed to subtract .25 points if you miss a question, if you can rule out one answer then you should go ahead and guess (assuming there are only 4 answers) because then you will have a 33% chance of getting it right versus the possibility of losing .25 points.
  6. The most common answers on tests are either “B” or “C”. So if you have no idea about the answer, guess one of those.
  7. If there is an all or none of the above, take a close look at those. If there are not a lot of “all of the aboves” on the test, it’s likely that that is the answer.
  8. Do not pay attention to the number of letters that you’ve answered: “I’ve had 5 Ds in a row; that can’t be right.” If you’re doing this you’re likely over-analyzing the test. Sometimes you are right but it’s not worth the effort to focus on (unless you really know most of the test material {and how the teacher or professor makes her tests}).
  9. Don’t panic! Don’t be afraid to stop for a few seconds or a minute and clear your mind. It’s worth the effort if you are feeling anxious or too nervous or overwhelmed. Too much anxiety can ruin even a well-prepared test-taker.
  10. Think positively. Tell yourself that you can do well. Tell yourself that you are a good multiple-choice test-taker.
  11. Above all – PREPARE. Studying for multiple choice tests is different than studying for essay examinations. Read over all the salient material then read over it again (I find it helpful personally to read it multiple times quickly). Multiple-choice tests are usually about breadth and not depth.

Image by gillespinault.

Categories: education, learning, psychology, testing Tags:

Motor learning – It’s good being in the background

June 6th, 2007 No comments

This was a story I first saw on Digg today but it’s worth posting about here. Researchers at MIT recently published a study in Neuron (May 24, 2007 issue) that demonstrates a completely new way of looking at motor learning. From their article:

“In experiments on motor learning, it is often assumed that there is an underlying neural representation that is stable and that adaptation takes place on top of this stable background. Our experimental and theoretical results suggest a radically different picture. The experiments show that tuning curves of motor cortical cells are constantly changing even when performing a familiar task. Furthermore, when learning a new task, learning-related changes occur on top of this background of changing tuning curves” (Rokni, Richardson, Bizzi, & Seung, 2007, p. 661).learning_theory.jpg

They are proposing that the neuronal activity associated with motor learning is a little like a sail-less ship on the ocean. This ship not only goes up and down the waves as they come, it also drifts about somewhat randomly in response to the underlying and unstable movement of the water underneath. This analogy isn’t perfect but it is OK.

Learning is not only a component of the active responsive brain activity but also the somewhat random low-level “background noise” that is slowly “retuned” and “retunes” in response to motor learning. This background noise only affects the synapses very slowly but it has a noticeable effect: “According to our theory, this slowness is necessary to prevent the noise from erasing motor memories” (p. 663). They do believe that this unstable foundation for learning is linked to forgetting over time. The researchers also state that there may be many ways that neurons can represent essentially the same behavior: “any single behavior can be realized by multiple configurations of synaptic strengths” (p. 653).

Anyway, the article was an interesting read and well worth the time if you have any interest in cognitive psychology. [The posted image is directly from the article in Neuron and is ©2007 Elsevier Inc].

Reference

Rokni, U., Richardson, A. G., Bizzi, E., & Seung, H. S. (2007). Motor learning with unstable
neural representations. Neuron, 54, 653-666.

Categories: cognition, learning, psychology Tags:

Dopamine, the Basal Ganglia, and Learning

May 7th, 2007 No comments

A significant proportion of dopamine (DA) is produced in the substantia nigra pars compacta (SNpc) and is carried to the striatum via the nigrostriatal pathway. While this pathway has been traditionally linked with motor functioning, recent research has implicated striatal DA involvement in language (Crosson, 2003) and learning (Seger, 2006). One disease in which there is considerable DA disruption is Huntington’s Disease (HD). In HD the head of the caudate is typically the first brain structure affected by neuronal cell loss. This cell loss not only affects connections with the SNpc but also affects the connections between the striatum and the prefrontal cortex. In HD the disruption of these dopaminergic pathways leads to disruptions in motor and cognitive functioning.

How DA disruptions affect cognition has been explained by theories that are modifications of Mink’s model (1996) of center and surround (i.e., direct and indirect) basal ganglia regulation. Within the caudate there are two main families of DA receptors – D1 and D2. These receptors have been shown to have different functioning within the basal ganglia (Seger, 2006) – the D1 receptor is involved with the direct pathway and the D2 receptor is involved in the indirect pathway. The D1, or direct pathway, can be viewed as increasing the strength of the signal of the desired response while the D2, or indirect pathway, serves to reduce the noise of the competing undesired responses. Dopaminergic systemic disruption in HD should thus decrease the signal-to-noise ratio, which results in the person having a greater difficulty selecting the desired response (see model below).

Center-surround model of basal ganglia-based learning and memory

*Model based on Mink (1996) and Frank, Seeberger, and O’Reilly (2004)

There is evidence that in early stages of Huntington’s disease, D2 receptors are the first to be affected, with less binding occurring at D2 receptors presumably due to receptor loss. As the disease progresses, the D1 receptors also start to become depleted, with the end result of widespread DA dysfunction (Glass, Dragunow, & Faull, 2000). This DA dysfunction possibly affects verbal learning and recall by impacting the indirect pathway in the early stages of HD and indiscriminately the whole direct and indirect system in later stages of the disease process.

References

Crosson (2003). Left and right basal ganglia and frontal activity during language generation: Contributions to lexical, semantic, and phonological processes. Journal of the International Neuropsychological Society, 9, 1061-1077.

Frank, M. J., Seeberger, L. C., & O’Reilly, R. C. (2004). By carrot or by stick: Cognitive reinforcement learning in Parkinsonism. Science, 306, 1940-1943.

Glass, M., Dragunow, M., & Faull, R. L. M. (2000). The pattern of neurodegeneration in Huntington’s disease: A comparative study of cannabinoid, dopamine, adenosine and GABAA receptor alterations in the human basal ganglia in Huntington’s disease. Neuroscience, 97(3), 505-19.

Seger, C. A. (2006). The basal ganglia in human learning. Neuroscientist, 12(4), 285-290.