John Lewis has changed its carefully constructed formula for their Christmas advert in 2016, Buster the Boxer.

The retailer returned to a more traditional heart-warming tone, after last year's Man on the Moon was perceived to be too melancholic by some viewers.

Still preparations for the advert have started as early as February and the latest campaign was created by Adam&EveDBB and directed by Dougal Wilson, who also worked on the three previous editions.

John Lewis estimates that since 2012 its sales have increased more than 35 per cent thanks to the success of its Christmas advertising. The retailer is also said to bring psychologists into the process to help them emotionally engage with viewers.

We spoke with marketing experts and consumer neuroscience specialists about the subtle techniques the retailers uses to connect with its fans.

1. Triggering your memory with a strong narrative

To have greater impact advertisers need to make sure their messages are taken on board by our memories.

There are several ways to do this, but John Lewis picks the strongest aspect - intrigue - and uses it to great effect.

John Lewis Christmas advert - Twitter reacts

Heather Andrew, UK chief executive of consumer neuroscience specialists Neuro-Insight, said: "Our brains love a story, particularly including puzzles with question and answer patterns. John Lewis played on this perfectly with a series of teaser ads featuring the nodding Buster, which led up to the grand reveal this morning."

"In the ad itself, we see Buster nodding away again, and as the trampoline is constructed we receive more clues about how this story might conclude. This gradually unfolding storyline is what keeps us engaged, with the final pay-off being Buster himself getting his own bounce on the trampoline."

Will McInnes of Brandwatch added: "As marketers, we know that a great ad is all about eliciting emotions. It’s classic big brand storytelling, meets distribution in the social age. Essentially people won’t share boring content and John Lewis knows it. In a world where our attention is pulled in so many different directions, it’s a reminder that a good story still matters."

2. Using animal to boost your emotional response

John Lewis has teamed up with The Wildlife Trusts this Christmas, which is why animals are a central part of their campaign.

John Lewis Launches 2016 Christmas Advertising Campaign ‘Buster The Boxer’

This is a smart move considering including animals can deliver a boost to viewer's emotional responses, according to Neuro-Insight’s own research supported by TV advertising body Think box.

3. A song that you will remember

Music is integral to the impact and success of an advertising campaign, and never more so than at Christmas when retailers and brands are battling for customer attention. If you consider what makes a Christmas ad really stand out and stick in people’s minds long after the spot has ended, it’s often the music.

Jess Nicks, a music consultant at Audio Network told The Independent: "John Lewis has successfully risen above the festive noise by artfully combining strong story-telling and imagery with impactful music. For a retailer that makes 40 per cent of its profit over the Christmas quarter, capturing the attention of consumers is critical."

Soft female vocals work well for Christmas campaigns as they lend an intimate feel to a story and help build an emotional connection between the brand and consumer, according to Nicks.

She said: "There has been a real shift away from traditional Christmas songs, with brands and agencies being more creative with the music they sync. Play it too safe by using anything too traditional and stereotypically festive and you’re in danger of your ad being forgotten in a sea of attention-grabbing soundtracks."

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4. A feel good factor advert

John Lewis said it had aimed for a sense of fun with its latest campaign, after 2016 had proved to be "quite a year".

The reaction to the advert was broadly positive with some viewers saying it came as a "welcome relief".

Maria Vardy, managing director at Jaywing, said: "This year sees a beautifully simple idea that transcends archetypes, ages and demographics. The ad provides a moment of escapism, warmth and enough of a feel good factor to deliver the perfect antidote to what has been, quite frankly, a depressing year of media coverage."

Amelia Torode, chief strategy officer TBWA\London, an agency whose brands include Airbnb and Lidl, said: "We also respond hugely positively to humour, typically we remember ads that make us smile or laugh. Advertising that brings together emotion, humour and everyday situations have been proved to work 15% harder than the average.