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This cover image released by Capitol Records shows "Witness," the latest release by Katy Perry. (Capitol Records via AP) Image Credit: AP

Katy Perry’s hair isn’t the only thing that’s shortened in recent months.

When the singer unveiled in February that she’d completed a new album, her first since 2013’s Prism, she used the phrase “purposeful pop” to describe the music. Such an expression suggested she had taken on a political edge following the election of Donald Trump.

Given Perry’s established flair for cheeky party tunes such as Last Friday Night (T.G.I.F.) and vivid young-love songs such as the immortal Teenage Dream, this felt like reason to worry.

Yet Chained to the Rhythm, the album’s lead single, turned out to be great: a sly condemnation of fake news that understands its own role in getting people to “dance to the distortion,” as she puts it over producer Max Martin’s shimmering disco groove.

It was enough to make you want to hear the singer’s deepest thoughts on climate change — provided her attention span could sustain them.

But by April, Perry appeared to have lost interest in purposeful pop. Her next single was the raunchy Bon Appetit, complete with a regrettable buffet metaphor, followed by Swish Swish, her supposed takedown of Taylor Swift (who’d dissed Perry with 2014’s Bad Blood). Both failed to crack the top 40.

Now comes the full album, titled Witness, and it’s more jumbled still, with would-be self-empowerment anthems next to earnest ballads lamenting the end of a relationship; Perry’s many collaborators run the gamut from Martin and his team of songwriters to the veteran bassist Pino Palladino, known to classic-rock fans for his membership in the Who.

One reasonable response here is, So what? Variety is a condition of modern pop, in which big-ticket albums are typically assembled by committee; sometimes the result even captures something of our addled era, as with Beyonce’s dizzying Lemonade.

But Witness, whose singles keep stalling out like Trump’s travel ban, diagnoses only Perry’s desperation for a hit.

Hey Hey Hey plays like a weak attempt to duplicate the success of her uplifting 2013 smash Roar, this time with a paper-thin tune and clunky words about being “Marilyn Monroe in a monster truck.”

Roulette has a sturdier melody but none of the witty specifics of Perry’s earlier exhortations to cut loose; Bigger Than Me borrows the sleek sensuality of Selena Gomez’s recent records without adding original flavour.

And then there are forgettable team-ups with hip-hop’s Mike Will Made It (Tsunami) and Corin Roddick of the Canadian indie duo Purity Ring (Mind Maze). Each is alert to the idea that pop welcomes unexpected pairings right now — think Calvin Harris and Frank Ocean, or Justin Bieber and Luis Fonsi — yet both stop short of true cooperation.

Witness contains strong moments beyond Chained to the Rhythm, which still feels like the beginning of an intriguing project, one Perry should return to if our politics continues to devolve (and after she tires of her gig on ABC’s American Idol reboot).

Her singing is as forceful as ever in Pendulum, a gospel-accented number produced with real swing by Jeff Bhasker, while the slithering Power puts her vocals against soulful textures that draw out new grit.

And however petty its inspiration, Swish Swish is a delight as Perry rhymes “another one in the basket” with “another one in the casket” over Duke Dumont’s thrusting ‘90s-house beat. But it’s hard to tell what each track has to do with the others, a problem this one-woman charisma factory has never experienced before.

After Swish Swish, Perry moves on to Deja Vu, in which she describes being stuck in a toxic relationship that never changes.

“Every day’s the same/Definition of insane,” she sings, “I think we’re running on a loop.”

That focus would’ve been better applied to her work.