Rats (5) Psychology (5) Ratas (5) Psicología (5) Animals (4) Animales (4) Labor (3) Time (3) Devaluation of currency (3) Consumption (Economics) (3) Devaluación (3) Frustración (3) Estudio (3) Datos (3) Trabajo (3) Tiempo (3) Consumo (3) dévaluation (3) Drugs of abuse (2) Sugar (2) Human behavior (2) Essays (2) Essay (2) Alcohol (2) Experimentos (2) Alcohol (2) Ensayos (2) Ensayo (2) Drogas (2) Conducta (2)