Prof Andrew Ng of Stanford University, and a co-founder of Coursera, has an interesting article on how you can Learn to Speak or Teach Better in 30 Minutes with the help of a video camera or a webcam.
He points out that athletes and musicians improve by picking challenging/difficult tasks and practicing those until they improve. Why don’t we do that with teaching / public speaking?
Deliberate practice is common in music and in sports, but is rarely used in the context of speaking or teaching. In fact, knowledge workers in most disciplines rarely engage in deliberate practice. This limits how rapidly we get better at our jobs; it also means that deliberate practice might help you progress faster than your peers.Key elements of deliberate practice include:
Rapid iteration.
Immediate feedback.
Focus on a small part of the task that can be done in a short time.
Here’s a 30 minute deliberate practice exercise for improving your presentations:
Select a ~60 second portion of a presentation that you made recently, or that you plan to make.
Record yourself making that 60 second presentation. Use a webcam, camcorder, or your cellphone video camera to capture video and audio.
Watch your presentation. If you haven’t seen yourself on video much, you’ll be appalled at how you look or sound. This is a good sign; it means that your speaking ability is about to improve dramatically.
Decide what you’d like to adjust about your presentation. Then go back to Step 2, try again, making any changes you think will improve your speaking.
Repeat the cycle of recording, watching, and adjusting 8 – 10 times.
Read the full article for more details, including a FAQ at the end.
it is understood that light rays travel slower through denser medium (such as water/glass) compared to air. The same is true for sound waves, it has different speeds when it travels through different media. But why does light bend while sound doesn’t?
It is interesting that this question does not occur to most students (including me!) when they are studying in school.
Here is the answer, as far as I can tell:
Sound refracts just like light, but the issue is that we just don’t care as much.
Let’s go step-by-step through this.
We care far more about refraction of light and far less about refraction of sound because our eyes are able to very precisely locate the source of most light rays, whereas our ears are pretty bad at precisely locating the source of a sound. Where did a particular sound come from? The best we can do is “left” or “right” and “near” or “far”. So, even though sound refraction is happening all the time, we don’t really notice or care.
That brings us to the next question: why did our senses evolve in such a way that we can locate light precisely, but not sound?
The reason has to do with the fact that in case of sounds in day-to-day life, diffraction is a far more important phenomenon than refraction. Diffraction is the bending and spreading of waves when they encounter objects or slits of a size comparable to the wavelength of the wave. Now, the sound that humans are normally able to hear have wavelengths from 2cm to 2m (more precisely, 1.7cm to 1.7m; by contrast, visible light has wavelengths that are from 400 to 700 nanometers). And considering the number of different things in our environment that are of this size, sound waves are pretty much diffracting like crazy all over the place. Which makes it hopelessly confusing to precisely locate sources of sound.
This means that even if we had ears that were capable of precisely locating the source of a sound, it would be pointless because all the diffraction would completely confuse the system. In other words, precise location of sound is pretty much not worth trying for in most normal settings. (i.e. it wasn’t worth it for us to try to evolve precise sound-locating organs.)
There are two common situations where precise location based on sound waves becomes important. The first is echolocation used by bats. The other is ultrasonography (i.e. ultrasound imaging used in medical diagnostics). It is left as an exercise to the motivated reader to figure out why both these applications use “ultra” sound – i.e. 50KHz in case of bats, and 2 to 20 MHz in case of ultrasonography. (Hint: how is the frequency of the sound related to the wavelength?)
Click on the image to see full-size.
And refraction is an important effect in ultrasonography. Here is a picture, from a scholarly article on ultrasonography, talking about how, sometimes, multiple images of the same thing get created in an ultrasound image due to the effect of refraction.
Here is a colour picture of the same phenomenon, just because people like color:
This is an ultrasound in which the patient appears to have two aortas, which happens due to the refraction of ultrasound waves across muscle and fat tissues. (Image credit: Nevit Dilmen via Wikimedia commons.)
Another interesting artifact of refraction of sound is the fact that sound appears to travel much farther at night or early morning.
At night (or on the surface of a water body), the air near the surface is cool, but higher layers haven’t yet cooled down, so as sound travels upwards at an angle, it gets refracted downwards, and ends up travelling as shown in the image. Often, the direct sound path will have obstructions while the path through higher layers of air will be clear. Click here for a page with detailed explanations of various effects related to refraction.
Another mind-blowing aspect of refraction is this:
If light is going from point P in in one medium (e.g. air) to point Q which is in another medium (e.g. water), then the fastest path to go from point P to point Q (given the speed of light in the two media) is exactly the same path as that actually taken by light after refraction.
Here is an interesting math problem which uses this principle. A lifeguard is sitting on a beach, some distance from the edge of the water. He becomes aware of a person drowning, as seen in the figure below. The guard must reach the swimmer in as little time as possible. Since the guard can run faster on sand than she can swim in water, it would make sense that the guard cover more distance in the sand than she does in the water. In other words, she will not run directly at the drowning swimmer. Your task involves determining the optimal entry point into the water in order to reach the drowning swimmer in the least amount of time.
The life-guard runs on sand faster than he can swim. Which path takes him to the swimmer fastest?
The solution to this problem is to use Snell’s Law of Refraction to determine the path of the lifeguard. The same principle also applies to shortest path via reflection. See Heron’s shortest path problem for an example. The advanced reader is encouraged to try solving the spider and the fly problem and spending some time wondering whether there is any relationship between that solution and Heron’s shortest path problem.
(Stuff like this makes me feel that I should should start a summer class for high-school students where we just discuss random science and maths stuff like this – no syllabus, no targets, no entrance-exam-coaching, just random discussions that start somewhere and end up somewhere else.)
According to the article, here is what results in highest chances of success:
Find managers (or other seniors) who will “sponsor” you (i.e. take an interest in advancing your career)
Be politically savvy
Convincing people with rational arguments works better than lying to them
Flattery works (especially if the target does not realize you’re trying to flatter them; but even when the target realizes it)
Act modest
Avoid blatant self-promotion
Here are some interesting excerpts which give interesting data-points and actual numbers from the study:
Ng et al. performed a metastudy of over 200 individual studies of objective and subjective career success. Here are the variables they found best correlated with salary:
Predictor
Correlation
Political Knowledge & Skills
0.29
Education Level
0.29
Cognitive Ability (as measured by standardized tests)
0.27
Age
0.26
Training and Skill Development Opportunities
0.24
Hours Worked
0.24
Career Sponsorship
0.22
(all significant at p = .05)
(For reference, the “Big 5” personality traits all have a correlation under 0.12.)
Before you get carried away, remember this:
Before we go on, a few caveats: while these correlations are significant and important, none are overwhelming (the authors cite Cohen as saying the range 0.24-0.36 is “medium” and correlations over 0.37 are “large”).
This table gives an idea of which tactics work best for career success. Higher numbers are good. Lower numbers indicate that those tactics don’t really work. Negative numbers indicate that those tactics will actually hurt your chances.
Recently, Higgins et al. reviewed 23 individual studies of these tactics and how they relate to career success. Their results:
Tactic
Correlation
Definition (From Higgins et al.)
Rationality
0.26
Using data and information to make a logical argument supporting one’s request
Ingratiation
0.23
Using behaviors designed to increase the target’s liking of oneself or to make oneself appear friendly in order to get what one wants
Upward Appeal
0.05
Relying on the chain of command, calling in superiors to help get one’s way
Self-Promotion
0.01
Attempting to create an appearance of competence or that you are capable
of completing a task
Assertiveness
-0.02
Using a forceful manner to get what one wants
Exchange
-0.03
Making an explicit offer to do something for another in exchange for their doing what
one wants
(Only ingratiation and rationality are significant.)
This site has a lot of information on how to make rational appeals, so I will focus on the less-talked-about ingratiation techniques.
So, modesty is good, self-promotion is bad. Here are details of how to present yourself:
Self-presentation is split further:
Tactic
Weighted Effect Size
Comment
Modesty
0.77
Apology
0.59
Apologizing for poor performance
Generic
0.28
When the participant is told in generic terms to improve their self-presentation
Self-promotion
-0.17
Nonverbal behavior and name usage
-0.14
Nonverbal behavior includes things like wearing perfume. Name usage means referring to people by name instead of a pronoun.
And finally some more details about flattery:
If you are talking to your boss, your tactics should be different than if you’re talking to a subordinate. Other-enhancement (flattery) is always the best tactic no matter who you’re talking to, but when talking to superiors it’s by far the best. When talking to those at similar levels to you, opinion conformity comes close to flattery, and the other techniques aren’t far behind.
Unsurprisingly, when the target realizes you’re being ingratiating, the tactic is less effective. (Although effectiveness doesn’t go to zero – even when people realize you’re flattering them just to suck up, they generally still appreciate it.) Also, women are better at being ingratiating than men, and men are more influenced by these ingratiating tactics than women.
Read the full article, it has a bunch of interesting references that the motivated reader is urged to read.
