A method for controlling a computer process in a personalised manner in a computer system (1,30), comprising the following steps: determining (50, 51, 82, 83) at least one chromatic iso-luminance information (g 2, b 2) for an individual, the determination of an iso-luminance information comprising the following steps: submitting the individual to at least one multicoloured, typically bicoloured, dynamic stimulus comprising displaying, on a display device of the computer system, a multicoloured, typically bicoloured pattern, at least two colours of which are periodically inverted at a so-called marking frequency (F tag), controlling a change overtime of at least one (C 2) of the colours of the multicolour pattern when displaying the dynamic multicolour stimulus, to vary the displayed luminance of that colour and to vary a luminance difference between the two colours, acquiring, (42, 43, 44) by an image acquisition device, an oscillatory response (SIG resp) of at least one pupil of the individual, when displaying the dynamic multicoloured stimulus, generating (46, 48), from the acquired response, a signal (SIG power, APPROX power) representative of the power of the oscillatory response (SIG resp) of the pupil as a function of the change over time of at least one of the two colours and of a difference in luminance between the two colours when displaying the dynamic multicolour stimulus, and determining the bicolour iso-luminance configuration of the two colours in the dynamic multicolour stimulus corresponding to a minimum of the signal representative of the power (SIG power, APPROX power), and using (54, 85) the at least one chromatic iso-luminance information thus determined as process input data in the computer system. determining (50, 51, 82, 83) at least one chromatic iso-luminance information (g 2, b 2) for an individual, the determination of an iso-luminance information comprising the following steps: submitting the individual to at least one multicoloured, typically bicoloured, dynamic stimulus comprising displaying, on a display device of the computer system, a multicoloured, typically bicoloured pattern, at least two colours of which are periodically inverted at a so-called marking frequency (F tag), controlling a change overtime of at least one (C 2) of the colours of the multicolour pattern when displaying the dynamic multicolour stimulus, to vary the displayed luminance of that colour and to vary a luminance difference between the two colours, acquiring, (42, 43, 44) by an image acquisition device, an oscillatory response (SIG resp) of at least one pupil of the individual, when displaying the dynamic multicoloured stimulus, generating (46, 48), from the acquired response, a signal (SIG power, APPROX power) representative of the power of the oscillatory response (SIG resp) of the pupil as a function of the change over time of at least one of the two colours and of a difference in luminance between the two colours when displaying the dynamic multicolour stimulus, and determining the bicolour iso-luminance configuration of the two colours in the dynamic multicolour stimulus corresponding to a minimum of the signal representative of the power (SIG power, APPROX power), and submitting the individual to at least one multicoloured, typically bicoloured, dynamic stimulus comprising displaying, on a display device of the computer system, a multicoloured, typically bicoloured pattern, at least two colours of which are periodically inverted at a so-called marking frequency (F tag), controlling a change overtime of at least one (C 2) of the colours of the multicolour pattern when displaying the dynamic multicolour stimulus, to vary the displayed luminance of that colour and to vary a luminance difference between the two colours, acquiring, (42, 43, 44) by an image acquisition device, an oscillatory response (SIG resp) of at least one pupil of the individual, when displaying the dynamic multicoloured stimulus, generating (46, 48), from the acquired response, a signal (SIG power, APPROX power) representative of the power of the oscillatory response (SIG resp) of the pupil as a function of the change over time of at least one of the two colours and of a difference in luminance between the two colours when displaying the dynamic multicolour stimulus, and determining the bicolour iso-luminance configuration of the two colours in the dynamic multicolour stimulus corresponding to a minimum of the signal representative of the power (SIG power, APPROX power), and using (54, 85) the at least one chromatic iso-luminance information thus determined as process input data in the computer system.