While short-term memory encodes information acoustically, long-term memory encodes it semantically: Baddeley (1966) discovered that, after 20 minutes, test subjects had the most difficulty recalling a collection of words that had similar meanings (e.g. big, large, great, huge) long-term.
Mentres a memoria a curto prazo codifica a información acusticamente, a memoria a longo prazo codifícaa semanticamente: Baddeley (1966) descubriu que despois de 20 minutos, os suxeitos testados tiñan moita dificultade en recuperar coleccións de palabras con significados semellantes (ex. cova, furna, fenda...).