Adjustment mechanism for motor vehicle seat, comprising a first component able to move relative to a second component along a first degree of freedom, and comprising: at least a first and a second sensor which are mounted on the first component, at least one plurality of protuberances provided on the second component, said protuberances being spaced apart from one another along the first degree of freedom, said first sensor being mounted facing at least one plurality of protuberances so as to be able to detect the presence or absence of a protuberance facing said first sensor during a relative movement of the first and second components along the first degree of freedom, said second sensor being mounted facing at least one plurality of protuberances so as to be able to detect the presence or absence of a protuberance facing the second sensor during a relative movement of the first and second components along the first degree of freedom, the sensors being positioned so that there is a phase difference between the signals detected by the two sensors, the adjustment mechanism further comprising an electronic control unit able to determine a direction of movement of the components in relation to one another, from said detected phase difference, wherein: said first and second sensors are each respectively facing a plurality of protuberances, an inter-sensor distance, corresponding to a distance between said first and second sensors, is different both from an offset between the patterns of the pluralities of protuberances, and from a sum of said offset and an integer multiple of said length of a pattern or patterns, the offset corresponding to a difference between a position of a given protuberance of one of the pluralities of protuberances, and the position of a protuberance of the other plurality of protuberances, located opposite said given protuberance, the length of said pattern or of each of said patterns corresponding to a sum of a length of a protuberance and a length of a space between said protuberance and an adjacent protuberance of said plurality of protuberances along the first degree of at least a first and a second sensor which are mounted on the first component, at least one plurality of protuberances provided on the second component, said protuberances being spaced apart from one another along the first degree of freedom, said first sensor being mounted facing at least one plurality of protuberances so as to be able to detect the presence or absence of a protuberance facing said first sensor during a relative movement of the first and second components along the first degree of freedom, said second sensor being mounted facing at least one plurality of protuberances so as to be able to detect the presence or absence of a protuberance facing the second sensor during a relative movement of the first and second components along the first degree of freedom, the sensors being positioned so that there is a phase difference between the signals detected by the two sensors, the adjustment mechanism further comprising an electronic control unit able to determine a direction of movement of the components in relation to one another, from said detected phase difference, wherein: said first and second sensors are each respectively facing a plurality of protuberances, an inter-sensor distance, corresponding to a distance between said first and second sensors, is different both from an offset between the patterns of the pluralities of protuberances, and from a sum of said offset and an integer multiple of said length of a pattern or patterns, the offset corresponding to a difference between a position of a given protuberance of one of the pluralities of protuberances, and the position of a protuberance of the other plurality of protuberances, located opposite said given protuberance, the length of said pattern or of each of said patterns corresponding to a sum of a length of a protuberance and a length of a space between said protuberance and an adjacent protuberance of said plurality of protuberances along the first degree of said first and second sensors are each respectively facing a plurality of protuberances, an inter-sensor distance, corresponding to a distance between said first and second sensors, is different both from an offset between the patterns of the pluralities of protuberances, and from a sum of said offset and an integer multiple of said length of a pattern or patterns, the offset corresponding to a difference between a position of a given protuberance of one of the pluralities of protuberances, and the position of a protuberance of the other plurality of protuberances, located opposite said given protuberance, the length of said pattern or of each of said patterns corresponding to a sum of a length of a protuberance and a length of a space between said protuberance and an adjacent protuberance of said plurality of protuberances along the first degree of