The phrase "an additional stimulus" is correct and usable in written English.
It can be used when referring to something extra that provokes a response or reaction, often in contexts related to psychology, economics, or biology.
Example: "The researchers introduced an additional stimulus to observe how it affected the participants' behavior."
Alternatives: "a supplementary stimulus" or "an extra stimulus".
An incentive system may provide an additional stimulus for operators with a view to achieving the requisite increase in passenger revenue and reduction in individual transport by motor vehicle.
In addition, chronic persistent virus infection in the CNS may provide an additional stimulus for microglial activation through Toll-like receptors.
In Angola, diamond production in the northwest was an additional stimulus for settlement.
Even in the more integrated city environments there has not be an additional stimulus to manage the demand for travel.
Higher rates would probably push up the cost of mortgages as well as business borrowing, offsetting any lift that came from an additional stimulus program.
Legislative proposals to raise the asset thresholds at which various compliance requirements are imposed on banks should provide an additional stimulus.
In addition to identifying retinotopic visual areas, we performed an additional stimulus-area localizer to identify voxels in these areas that responded most strongly to flickering checkerboard stimuli with dimensions similar to those used in our visual persistence experiment.
Circulating DAMPs, may therefore be an important additional stimulus for increasing peripheral chemoreceptor activity, beyond (and in addition to) previously identified cytokine mediators (10).
(Here, Blinder says, the communications failure began to take its toll, because Obama did not make the case for a big enough stimulus or for a necessary additional stimulus later).
Markets fell on Wednesday after the article and other news from Beijing indicated that China's planners remained cautious about engaging in a huge additional stimulus program.
Sport-specific training methods for team sports using the stress of hypoxia as a strong additional stimulus with specifically designed training models are arguably promising methods.
