Glider

No, the brain modulates simple reflex action. Input from the brain is not necessary for the action to occur. I accept that there is a range of reflex types but the OP asked about the patellar reflex, which along with other reflexes such as the escape reflex is a simple (i.e. spinal) reflex. Spinal reflexes are those in which "the sensory stimuli arise from receptors in muscles, joints and skin, and in which the neural circuitry responsible for the motor response in entirely contained within the the spinal cord.(bold added)" (Kandel, Schwarts & Jessell, 1991. p565). I accept that descending influences from higher CNS areas modulate the reflex response (the basis of diagnostic reflex testing) and can also use these simple spinal circuits to generate more complex behaviours, but that is not what was asked. The OP asked why these reflexes exist and I felt that the best response to a relatively simple question was a relatively simple answer. Reference: Kandel, E. R., Schwarts, J. H. and Jessell, T. M. (1991) Principles of Neural Science (3rd Ed.). Prentice Hall International: UK.

Here, whilst masters and Ph.D. theses are scruitinised for plagiarism, it's not to the same degree as undergraduate work. The reason is that masters and Ph.D. work has to be novel and original (and sections are read by the directors of study) so there is generally less scope for cut & paste type stealing. Undergrad. work however, is the same old stuff, year after year and the scope is huge, especially with previous essays appearing on the intermaweb.

None. The reflex arc exists at the spinal level (althoough the spinal cord is still part of the CNS). Basically, the reflex arc consists of an interneuron which connects an afferent (sensory) nerve fibre to an efferent (motor) nerve fibre. When an incoming afferent signal of sufficient intensity passes into the dorsal horn of the spinal cord, it triggers the interneuron, which passes the signal to the efferent neurons in the ventral horn of the spinal cord and down to the appropriate muscle. Although the afferent signal will continue up the spinal cord to the brain (so we sense the contact), the motor impulse will have caused the muscle to contract by the time we feel it, so as far as the reflex goes, the afferent impulse continuing up to the brain is irrrelvant. In short, the reflex arc is an autonomous, functional unit existing at the spinal level that requires no input from the brain, conscious or otherwise.

Look at a glider in flight. The weight of the glider provides a downward force, the airofoil translates this into forward motion (airspeed) which provides lift. If a glider weighed nothing, it would go nowhere. There is no 'upward stroke'. Gravity acting on the rider, and the force generated by the rider 'jumping' dictate a downward force only. The hydroplane (which has to be moving forward anyway, hence the 'kick off' given by the rider at launch) translates the downward force into further forward motion (acceleration) which increases the speed of water over the 'plane increasing lift and resulting in the upward motion. At the top of the arc, the rider pushes down again, providing the energy that is tranlated by the 'plane into forward motion, and so it cyles. The hydroplane describes a sinusoid motion through the water ('porpoising'). This is also done by parascenders to gain forward speed in dead air. Your own body weight provided the downward force, and if you pull the brakes to make the wing almost stall, then release the brakes, the canopy dives (accelerating also). Then, you pull the brakes and the canopy flares (makes use of the increased airspeed (lift) to regain a bit of altitude), then you release the brakes and the canopy dives and so-on. If you get the frequency right, this increases your airspeed and the canopy 'porpoises' through the air faster and losing a lot less altitude than if you just pointed at the target and waited. Yes, that's why the rider has to give an initial 'kick off' to create forward motion. The downward thrust provided by the rider translates into acceleration, but without that initial forward motion, it would just be downward force and the thing would sink (same as a airofoil stalling). Yes, see above. It does to a degree. The contraption pivots on the forward plane(s) so the hydrofoil describes a vertical arc as it moves through the water. Hold your forearm in front of your face parallel to the ground. Now. keeping your elbow still, move your forearm up and down and notice the angle of your hand change from leading edge up to leading edge down. That's how it works. Not quite. That implies an 'active' upward stroke. The downstroke provides acceleration and increased lift. The increased lift results in the upstroke (which is passive). The rider bending his/her knees preparing for the next downstroke facilitates the upstroke. If the rider kept their knees straight, the upstroke would be impaired and the thing would sink.

Reflexes that persist to adulthood exist to prevent or limit injury. Other (infantile) reflexes like the grasping reflex seen in the feet of infants (e.g. the Babinski reflex) are left over from our evolutionary history (we no longer grasp with our feet) and dissapear within two years. If present after 2 years, it's considered abnormal. The knee-jerk (and related reflexes) are deep tendon reflexes. Essentially, they protect the joints. They are a way for the body to detect sudden passive extension/flexion of a joint and to engage oposing motor muscles quickly to compensate and prevent injury due to over extension/flexion. The speed is due to the reflex arc which a functional unit on its own and exists at the spinal level so signals don't have to travel to the brain to elicit a reaction. This saves time and also means that reflexes are entirely automatic and require no conscious input.

I wouldn't worry about the 'cut & paste' kids. When it comes to the crunch, you'll know what you're talking about. They won't. If you all go to Uni afterwards, you'll do well because of the good habits you've formed, and they'll hit a wall. 'Cut & Paste' is considered plagiarism at Uni, and the penalties can be swift and harsh.

Perhaps, but that's because it's an observation, not a value judgement. Psychological neoteny is what it appears to be, not what I feel about it, which is an entirely different thing. What I feel about it is that it is potentially dangerous and needs to be opposed at every instance. This is what education was supposed to be for. I believe we should forget the old "Respect people's beliefs" chestnut. We might respect their right to believe it, but I don't think you can ask a reasonable and logical person to respect the unreasonable and illogical. That's true. I think psychological neoteny involves (or results in) a number of elements as well as the main factor of the intuitive belief framework. I think it includes lazyness (unwillingness to critically evaluate the world or one's own beliefs), ignorance (being unaware of the current understanding of the reality of things), elitism (the need to belong to a group that is more 'right' and 'better' than others), fear (of one's own mortality and the idea of oblivion), superstition (misattribution of causal relationships) and external locus of control (the belief that events and features of one's own immediate environment are determined by luck, fate or powerful others). Moreover, the factors I listed would account intuitively for an individual being more willing to accept the easy answer without question (lazyness and superstition), particularly if that answer offers them redemption and a way of avoiding their own mortality in some way (fear), and if the individual is unaware of the illogical and unreasonable nature of that answer (ignorance) and if it also means joining a particular group who are 'in the know' and are 'saved' (elitism), and if it's delivered by a respected (powerful) other (external LOC). [EDIT]I just noticed, by this argument, religiosity would appear to be correlated with the weaknesses of humanity. Hmm. That fits. I may be entirely wrong, but it would support my 'Religion-is-the-worst-crime-against-humanity-ever-perpetrated' hypothesis.[/EDIT]

I have seen these before. The mail element is the 'wing', the main cross member that is submerged. This is a hydroplane and acts like a dolphin's tail. The contraption doesn't actually float with a rider on board. Downward force from the rider cause forward thrust and lift (even the force of getting on board) in the same way as the downward force ('falling') of a glider causes air to pass over the wing providing lift. The hydroplane moves forward and rises in the water then the rider pushes down again. The thing essentially 'porpoises' through the water. As with any wing, it requires a minimum airspeed (or in this case, water speed) to provide sufficient lift. Below that, the thing will stall and sink.

I'm also on Bonsai chat and Bonsai Talk (I like bonsai).

The water isolates the external metal components of the lightbulb to stop the contact end arcing out. The filament is inside the glass bulb so the arcing there is isolated too.

That's interesting. It would suggest then that some people (e.g. proponents of creationism) are subject to a kind of psychological neoteny. It gives a new slant to "Suffer the little children to come unto me", doesn't it? It would suggest that those who are thinking within the child-like framework of the 'intuitive beliefs' of purposeful design of things are more likely to 'go to Him' as 'He' offers a view on existence more sympathetic to their own cognitive framework. It would explain a lot.

Assuming I understand your question correctly, it's due to pressure. The water coming out of the lower hole has more water on top of it (and water is quite heavy), so it comes out under higher pressure. The water at the higher hole has less water on top of it and so comes out at lower pressure.

Plenty. The University of Surrey have an Environmental Psychology Research Group and run an MSc in Environmental Psychology. Elsevier publish a journal devoted to the topic 'The Journal of Environemntal Psychology'. That's where I would look for new work in the area. I don't know about the USA though. If I were you, I'd start with the journal and see where the work is coming from.

Well put.

I think we still need to define 'jerk'. it's going to be hard to reach a concensus for as long as jerk means different things to different people. It's like trying to explain why some people are gits.

I second that. Welcome to the forum. It's nice to meet someone with a realistic perception of Psychology and an interest in the subject. We look forward to chatting with you.

"We train young men to drop fire on people. But their commanders won't allow them to write "f**k" on their airplanes because it's obscene!" -Kurtz, Apocalypse now

Quite. It's as well to remember that not only is the inflammatory response a first line against infection, but healing in many cases is also an inflammatory process. Bone healing is a good example.

I would say so, because pollution makes that habitat no longer habitable. You don't have to destroy a house to make someone homeless, you just have to make it impossible for them to live in it.

True, but not really relevant. I think what Sayonara was referring to is the academically acknowledged difference between 'sex' and 'gender', where sex refers to 'male' and 'female' whilst gender refers to 'masculine' and 'feminine'. Sex is a dichotemous biological (genotypical) state and gender is a sociobehavioural construct consisting of a number of gender traits that can exist in combination. Gender is the construct that forms a part of a person's self-identity and may or may not be congruent with their sex.

You would do well to widen your research. No it doesn't. It is only a psychotheraputic approach (one of many and not a particularly good or effective one in my opinion). It never had anything to do with 'uncovering the mysteries of human nature' and couldn't, even if it was applied in that way.

I think it comes down to there being broadly two types of student: those who want a degree and those who want an education. The former won't bother with the wheat/chaff thing and will happily copy whatever they find that sounds remotely relevant, from whatever crappy website they find it on. Happily, they're also dumb enough to cite the crappy websites (because, of course, they'd hate to get busted for plagiarism ). The latter tend to search out the original papers and read them. I strongly discourage an over-reliance on the 'browsing' approach and encourage more focussed searches from recognised sources. If I find 'cut and paste' from crappy websites, then it's the plagiarism route, every time. I haven't seen any evidence of that in my University, but Universities do seem to make it hard for tutors. If I suspect plagiarism, then I have to search out the original source, print it, highlight the plagiarised section(s) in both the student work and the source, copy them and take the copy to the school office, where they will review the case and make a decision. Even then, the outcome is not certain, the actual threshold of plagiarism being so vague. If we have accused a student of plagiarism and the office rule that it isn't, then it opens the tutor up to a whole bunch of claims from the student. This is the biggest hurdle I think. Whilst reporting plagiarism is not 'institutionally' discouraged, many people don't because of the fear of legal consequences should their case fail. These days, people tend only to report only the most absurdly obvious cases. I think it's a symptom of increasingly consumerist attitudes. By paying tuition fees, those students who just want a degree get the idea that they're 'buying' it; that we owe them a degree simply by virtue of their cheques clearing. Like all consumers, they feel they have the right to litigate should their 'goods' not be automatically provided within a reasonable period of their having paid for them. Universitites seem unwilling to make it clear to prospective 'clients/customers' that they are paying for an education and not a degree, and that the degree is only awarded if they can demonstrate that they acquired the education they paid for (i.e. learned something). I think this is because of the increasingly fierce competition to get bums on seats and they don't want to risk discouraging prospective students. The current government fad is 'widening participation' where Universities are being 'encouraged' to recruit students from lower socioeconomic backgrounds (conveniently avoiding any mention of their having increased tuition fees), stating that everybody has a right to higher education. I agree with that principle but, as with increasing numbers of students, the government seem unable to tell the difference between 'an education' (i.e. learning stuff) and 'a degree' (a piece of paper awarded to people who can demonstrate that they learned enough stuff). Everybody does have the right to an education, but along with that must come the right to fail (for whatever reason). You cannot dictate that a person must learn. Not everybody wants to. Not everybody can. [/RANT]

What? This doesn't make any sense. Are you trying to make inferences concerning neurological develpoment from psychoanalytical texts? Do subjective concepts have neurological structure? Have you accounted for neural plasticity? Do you have any evidence for your statement at all? True, and in any event, you (coburst) can't base any neurological inferences on Freud's work, because he rarely made any. Most of his explanations were metaphorical (e.g. 'steam engine' for 'sexual energy'). In the UK, the British Psychological Society insist that all modules contain an element of the 'history and philosphy' of Psychology. Again, true.

Thanks CharonY, I thought they were, but time takes it toll. That'd be useful Blike, thanks

Yep. I'm a bit hazy on the precise detail though. It's either that mechanical deformation of the membrane causes a locallised change in membrane potential that triggers voltage gated sodium channels, or that mechanical defomation directly causes ion channels to open (which causes a localised change in membrane potential...blah, blah). I think it's the latter, as I can't think of another way of inducing localised depolarisation.