), the researchers examined the "contrary prediction that positive self-statements can be ineffective or even harmful".
Over the course of two experiments, participants with low self-esteem who repeated a positive self-statement or focused on how that statement was true "felt worse than those who did not repeat the statement or who focused on how it was both true and not true".
Admittedly, neither study explores the impact of positive statements in schools, but both suggest that attempting to change students' perception of themselves through motivational messages could lead to problems. Indeed, the fact that posters make "generalised attempts" to alter a student's self-perception is their undoing, Hendrick feels.
"Firstly, student self-concept is both multidimensional and hierarchical," he says. "A student might have a very positive concept of self in English but a very negative one in maths.
"Secondly, student self-concept is both academic and non-academic and can be broadly categorised into seven subareas such as physical abilityappearance and peer relations as well as academic ability. So trying to manipulate these domain-specific issues through `all-purpose' positive interventions attempting to boost general self-esteem is likely to be ineffective."
There is another issue here, too, Hendrick believes. "Research shows that while there is a strong correlation between self-perception and achievement, the actual effect of academic achievement on self-perception is stronger than the other way round," he says. "Students who are taught well and given clear and achievable paths to academic success might well be creating a more positive perception of themselves than those given unproven interventions."
It is at this point that some advocates of the approach will point to Carol Dweck. Some believe that motivational posters are the very essence of her much-celebrated "growth mindset" theory. Dweck, however, does not agree.
She explains that sticking up motivational posters in classrooms and school corridors isn't, by itself, going to do any good; these positive messages have to be reinforced in other ways to have an impact.
Dweck is acutely aware that her work has in some instances been reductively misrepresented, and she feels that growth mindset is often misinterpreted as "praising any old effort and telling kids they can learn". In actual fact, she says, it's more about having an "optimistic belief that you can grow your own abilities through hard work, perseverance and help and instruction from other people".
"A lot of nuanced ideas get watered down when they are implemented very broadly, and it's always possible that people have implemented a less nuanced version that is less effective," Dweck says. "That is why we're working really hard to develop our own intervention and develop teacher practice modules so that teachers can really understand how to give the right praise, how to frame a new unit, or how to grade in a way that promotes a growth mindset."
Dweck is advocating not general compliments but targeted praise. Essential to that is a realism about what can be achieved. And this is where the motivational posters really fall down for many critics - they pretend we can all achieve everything.
Alex Quigley, head of research at Huntington School in York, says teachers should not get sucked into this attitude: "There is a danger for many students that they learn about mindsets and try their hardest but they fail and are left feeling worse because they applied effort and thought they could achieve anything.
"Not everyone will write like Shakespeare, but we can all be better writers with effort and deliberate practice. That is positive enough for me as a message and will give students the fuel to stick at their learning."
This sentiment is echoed by Oettingen, co-author of the study mentioned above and a professor of psychology at New York University and the University of Hamburg. She advocates an approach called Woop, which stands for "wish, outcome, obstacle, plan" (www.woopmylife.org). Oettingen argues that positive fantasies can actually be useful, but only if you "juxtapose them against the obstacles of reality".
"Positive fantasies are helpful for pleasure. They're helpful for situations where you cannot act, where you are just caught up in a situation when you can't do anything," she explains. "But as soon as you actually have the possibility to act, positive dreaming alone is not enough. You need to change gears and put the obstacles of reality that you foresee against these positive dreams - that's what we call mental contrasting and out of mental contrasting we developed the strategy that we call Woop."
Cause for optimism
Yet do we really want to tell our students that their chances are limited? Do we really want to put up more barriers than may already be in place? "Reach for your dreams and grab them - but only if you have a lot of luck, the right school tie and beat several hundred others with the exact same attributes as you" isn't quite such an optimistic message.
Vic Goddard, principal of Passmores Academy in Harlow and star of Educating Essex, certainly doesn't think this is the right attitude. He's a big fan of motivational posters; indeed, he has a poster outside his room saying "I am not telling you it is going to be easy, but I am telling you it is going to be worth it".
Goddard believes the posters act as a constant reminder that hard work leads to success and that they aid the school's efforts to tackle the underperformance of a small percentage of students.
"It would be ridiculously simplistic to say that on their own these messages are going to stop my `learning cowards' from disengaging when the lesson gets challenging," he explains. "However, as part of a coordinated range of activities, as well as the everyday and incredibly powerful conversations we have, they are having an impact. Just before anyone asks, `Have I got any good research proving that?' Yes I have, every day, in what I see and hear.
"And if the use of constant reinforcement of a message has no impact, why will the political parties spend millions doing just that [in the run-up to the general election] and why do incredibly impact-focused advertising companies spend billions every year? I'm sure they won't waste their time and, more significantly, their money."
Goddard has a point. Nike clearly believes its motivational "Just do it" slogan works judging by the millions it spends each year on advertising including the phrase - and it certainly seems to motivate people to buy the company's trainers.
Many teachers will argue that Hendrick is misunderstanding the use of the posters; they will say that of course their strategy does not rely solely on a motivational message pasted on to the classroom door. It's part of a mix, just one strand of a larger process. It's harmless.
Hendrick, however, maintains that motivational posters are damaging and urges a rethink. He sums up his position in the conclusion to his blog: "Motivational posters are a `daily boost of inspiration' for some and vomit-inducing for the rest of us but they also encourage us to take complex ideas and reduce them to something utterly trivial and seemingly life-changing, often far removed from their original premise.
"There are complex ideas that should be given time and space for us to critically reflect upon and resist the urge to summarise into a soundbite.As my old English literature tutor Professor Chris Baldick once quipped in a lecture: `Men are from Mars, women are from Venus and pop psychology is from Uranus.' "
An explanation of motivation theory in business terms.
"Thought for the day" displays.
Galvanise your class with this lesson on motivation.