"Plain packaging reduced unconscious triggers to smoke," BBC News reports.
This claim is based on two related experiments where smokers were either exposed to a picture of a branded pack of cigarettes, a picture of a plain pack (containing a graphic health warning), or nothing at all, and were asked to choose a reward of either chocolate or a cigarette.
Researchers found people exposed to the plain pack were, over time, 9% more likely to choose a chocolate reward compared with people exposed to the branded pack, so their consumption of cigarettes was reduced.
This study has inherent limitations, meaning we shouldn't really count on seeing a similar reduction in smoking through the use of plain packaging in the real world, as the study's authors acknowledge themselves.
Professor Marcus Munafò, a co-author of the study, explained: "In the natural environment, smoking may be governed by a whole range of factors … It is not clear to what extent plain packaging will reduce smoking when these other factors are at play."
The biggest real-world experiment is already underway in Australia, where plain packaging was introduced by law in 2012. Recent information released by the Australian government does show a subsequent modest reduction in smoking rates.
The study was carried out by researchers from the universities of Exeter and Bristol in the UK, and the University of New South Wales, Australia.
It was funded by the British Heart Foundation, Cancer Research UK, the Economic and Social Research Council, the Medical Research Council, and the National Institute for Health Research.
BBC News summarised the results of several related studies on plain cigarette packaging.
The Guardian reported on a study in the same journal looking at whether plain packaging would help reduce the number of people taking up the habit. This study is also available online to read for free.
This was an experimental study investigating how cigarette packaging influences smokers' desire to smoke.
The research team says that in current smokers, plain cigarette packs are less appealing, provoke less craving and motivation to purchase, reduce short-term self-reported smoking rates, and increase attention to health warnings when compared with branded packs.
Although these studies suggest plain packs may reduce smoking motivation, the research team thought further direct evidence of whether plain packs reduce the amount people smoke was needed to gain insight into the potential effectiveness of a plain packaging policy.
Experimental studies like this are useful in isolating single elements of a decision-making process in artificial laboratory conditions. But they don't reflect the more complex decision-making environment of normal life. A judgement call needs to be made about how relevant the experimental condition is to normal life, and this isn't an exact science.
The team reported two similar experiments: one small (n=23), the other larger (n=121).
Smokers had to choose between pressing a key that might earn cigarettes, or a key that might earn chocolate. They were uncertain about which key was most likely to pay off in each test.
Just before participants made each choice, they were presented with either a picture of a branded cigarette pack, a picture of a plain cigarette pack, or nothing (as a control). This aimed to show whether the pictures influenced choice preference.
Participants were eligible for the study if they smoked between 5 and 20 cigarettes a day every day of the week and smoked within one hour of waking. The average age in the larger group was 21, and they smoked an average of 10 cigarettes a day.
The combined results showed branded packs increased the probability of smokers choosing a cigarette by 10% compared to when nothing was presented. The plain packs did not. The implication is that plain packs are less effective at prompting smokers to purchase cigarettes compared with branded packs.
Branded pack pictures prompted a tobacco choice in 62% of decisions, compared with 53% using plain packaging. The difference – 9% – was rounded up to a cleaner-sounding 10% for the press release.
The team concluded that, "Plain packaging may reduce smoking in current smokers by degrading cue-elicited tobacco-seeking."
In the press release, co-author Lee Hogarth said that, "Our study demonstrated that, under some circumstances, plain packaging can reduce cigarette-seeking behaviour. Policymakers must consider how much weight to place on this observation when considering the potential pros and cons of introducing plain packing as a national policy."
This small study showed that priming adult smokers with a picture of a branded cigarette packet causes more of them to seek cigarettes compared with unbranded cigarettes – around 10% more.
But this study has problems, meaning we can't really rely on its findings. The biggest of these was fully acknowledged by the study authors themselves.
Professor Marcus Munafò, a co-author of the study, explained: "The experimental procedure only modelled the ability of pack stimuli to promote a cigarette-seeking choice.
In the natural environment, smoking may be governed by a whole range of factors, including tobacco withdrawal, the presence of other people smoking, time of day, and so on. It is not clear to what extent plain packaging will reduce smoking when these other factors are at play.”
The biggest real-world experiment is already happening in Australia, where plain packaging was introduced by law in 2012. The wider evidence showing whether plain packaging reduces smoking-related death and disease in adults or children was not discussed in this study, so we cannot comment. Taken on its own, this specific study adds weak evidence to the debate. There may be stronger evidence elsewhere.
On this point, the Addiction journal's editor-in-chief, Professor Robert West, said in the BBC article: "All the pieces are building the same picture, which is that it is going to have a reduction; none of the studies are pointing in the other direction." But he admitted it was not possible to know if plain packaging had reduced the number of young smokers in Australia.
He said the data was "suggestive, but not conclusive", as "the effect would have to be enormous for it to be picked up in the overall prevalence data".
The current UK government has pledged to introduce plain packaging legislation in this country in 2016. But there is a general election between now and then, so any government formed after that may have different plans and priorities.