Device for determining an atypical movement of a person, comprising - a housing, - a passive IR detection means in the housing, which means has a thermopile array in which a flat sensor means is arranged on a visible side of the housing such that IR radiation from one or more people in a measurement room in front of the visible side can be detected, and - an evaluation means in the housing, which means is coupled to the passive IR detection means and is configured, as part of a process for determining an atypical movement, to receive and evaluate IR detector signals which are provided by the passive IR detection means as a two-dimensional distribution of IR measurement signals and which indicate the presence of a detected person in the measurement room in order to determine an atypical movement of the detected person in the measurement room and to provide a signal indicating the determination of the atypical movement at a data output of the evaluation means, wherein the evaluation means is configured, in order to determine the atypical movement, for the two-dimensional distribution of IR measurement signals, - to carry out object identification in order to identify objects, - to analyze geometric data for the identified objects in order to extract feature data, wherein the geometric data is selected from the following group: a y-dimension, an x-dimension, a temperature center of gravity, an outline length, an energy density, an energy distribution, movements of the objects and a center of gravity of each of the objects, - to count the identified objects, and - to carry out a movement analysis for movements in the x, y and z directions for the identified objects for tracking and maintaining the object-related extracted feature data and as an activity index. - a housing, - a passive IR detection means in the housing, which means has a thermopile array in which a flat sensor means is arranged on a visible side of the housing such that IR radiation from one or more people in a measurement room in front of the visible side can be detected, and - an evaluation means in the housing, which means is coupled to the passive IR detection means and is configured, as part of a process for determining an atypical movement, to receive and evaluate IR detector signals which are provided by the passive IR detection means as a two-dimensional distribution of IR measurement signals and which indicate the presence of a detected person in the measurement room in order to determine an atypical movement of the detected person in the measurement room and to provide a signal indicating the determination of the atypical movement at a data output of the evaluation means, wherein the evaluation means is configured, in order to determine the atypical movement, for the two-dimensional distribution of IR measurement signals, - to carry out object identification in order to identify objects, - to analyze geometric data for the identified objects in order to extract feature data, wherein the geometric data is selected from the following group: a y-dimension, an x-dimension, a temperature center of gravity, an outline length, an energy density, an energy distribution, movements of the objects and a center of gravity of each of the objects, - to count the identified objects, and - to carry out a movement analysis for movements in the x, y and z directions for the identified objects for tracking and maintaining the object-related extracted feature data and as an activity index.