Formula 1 is to focus research on a transparent 'shield' device as bosses seek to finalise a frontal driver head protection system for 2018.
A decision to "prioritise" a forward clear screen was made at two rule-making meetings on Tuesday.
However, an FIA spokesman said the controversial halo device, tested by all teams last year, would be used next season if a shield did not work.
The FIA is committed to introducing additional protection in 2018.
A statement from the FIA said it would "carry out track tests on this [shield] system during this season in preparation for implementation in 2018".
The halo - a metal frame that arches over the driver's head from behind his shoulders and meets at central point at the front of the cockpit - is the only head-protection device that has so far proved suitable for the task of protecting drivers from large flying debris.
Red Bull trialled a screen system last season - which was dubbed the 'aeroscreen' - but it failed its FIA tests.
A new screen system, known as the shield, has now been proposed with a shallower angle than on the aeroscreen. This is the device that will be tested this year.
The FIA tests will focus firstly on ensuring that the screen is strong enough to deflect a wheel and tyre fired at it at 150mph, and then on whether there are other major issues such as visibility.
The halo has passed all these tests and is ready for introduction, but F1 has already backtracked on a plan to introduce it this year and continues to vacillate over it.
Doubts have arisen from some drivers and team bosses, who feel that its aesthetics are not appropriate for F1.
A number of other tweaks were made to the rules at the meetings of the strategy group of leading teams and bosses and the FIA F1 Commission.
- Drivers' names and numbers will be made clearer on all cars from the Spanish Grand Prix on 12-14 May
- Teams currently not on the strategy group - which has until now been restricted to Ferrari, Mercedes, Red Bull, Williams, McLaren and Force India - will be invited
- Controversial shark fins and so-called T-wings that have appeared on cars this season will be banned from 2018
- Next year, any race that is stopped with a red-flag period will be resumed from a standing start
- Measures will be taken to ensure that oil will not be used as fuel in 2018