SAN JOSE, CA: Spending on Google Shopping Ads rose sharply during the last quarter of 2014 as retailers turned away from text-based search spending to invest in image-based ad formats.

The quarterly Global Digital Advertising Report from Adobe Digital Index showed spending on shopping ads up 53% on the third quarter. And while this might have been expected during a holiday period when retailers are fighting hard for consumer dollars, it was also 47% up on the same period a year earlier.

At the same time Google Text Ad spending in the retail sector dipped 6%, indicative of a trend towards a more visual approach by retailers.

Text-based ads still dominate the SEM retail space, however, with an overall 80% share of clicks. Google takes the lion's share at 66% and Yahoo! Bing holds a 14% share.

Overall, Google Shopping Ads accounted for just 20% of all retail SEM clicks in the US, with Yahoo! Bing, which only recently added a similar feature, gaining a 0.7% share.

Tamara Gaffney, principal analyst for the Adobe Digital Index, predicted that shopping ads could constitute 30% of paid clicks by the fourth quarter of 2015, Forbes reported.

And, while Google Shopping Ads are currently focused on the retail industry, Gaffney suggested that similar image-heavy ads could work well in other sectors, such as travel and hotels.

The Adobe Digital Index report also looked how each type of digital advertising fared on different days of the week and highlighted some significant findings for marketers to bear in mind.

On mobile devices, consumer search click frequency was highest during the weekends, with share of mobile clicks on Sunday 17% higher than the average day.

Desktop search clicks ranked highest on Mondays, outperforming the rest of the week by 9%. And Friday had a higher share of Facebook posts, impressions, and interaction rates than any other day.

Data sourced from Adobe Digital Index, Forbes; additional content by Warc staff