Sebastian Vettel admitted that he had felt dizzy after trialling the new shield head protection systems on his Ferrari on Friday.
Vettel completed just a single installation lap at Silverstone with the new canopy-style device attached to the SF70H. Initially he reported that his view had been 'blurred'.
But in the afternoon, he expanded his reaction to the trial by saying that the new device had also made him feel dizzy.
"I don't think I need to talk about the pros. Obviously I know what it's for," said Vettel. "Cons: I tried it this morning, I got a bit dizzy.
"Forward vision is not very good," he added. "I think it's because of the curvature. You get quite a bit of distortion.
"You get quite a bit of downwash down the straights pushing the helmet forward," he said. "We had a run planned with it but I didn’t like it so we took it off.”
Sky Sports F1 analyst Pat Symonds explained what Vettel was referring to by 'downwash' in this instance.
"What he's describing is air spilling over and into the cockpit," he said, adding that CFD simulations last year had hinted at potential issues.
"We did see an awful lot of effect not just on the driver but on the engine inlet, on the rear wing, things like that," he said.
"I keep going on about aerodynamics, but we can't forget the aerodynamics on a Formula 1 car.
"This is really quite an immature technology that we're talking about."
Vettel also seemed to find is difficult to climb in and out of the cockpit of the car with the shield attached. However, he suggested that this wasn't a particular sticking point.
"For sure it doesn't help," he admitted. "I think it's more that - obviously getting in doesn't matter - but getting out, it's more about getting used to it. So that's not the main thing, I think."
The shield is set to be analysed further at the Italian Grand Prix in September. It replaces the now-abandoned 'halo' concept, which fitted a wishbone-like structure over the cockpit to protect the driver's head from impacts.