Allgemeine und Biologische Psychologie

humans

One could think that studies on humans differ principally from studies on animals. But is this necessarily so? Can’t we study human cognition in a way that is related to the cognition of non-human animals?

If there is a specific characteristic of human cognition, then it is our ability to understand and give meaning. Experiments on sensory memory employ stimuli that have little or no chance to elicit semantic content. Typically these are random stimuli. Therefore, for the study of pre-human cognition with human participants, sensory memory is the perfect tool.

Auditory sensory memory

In hearing, we can use the pitch of a sine tone to test auditory sensory memory - as long as you don't have absolute pitch. Another approach is to use random signals: our ability to detect the periodicity in periodic noise demonstrates our ability to remember non-semantic stimuli.

Auditory noise can be built by presenting a random waveform. In Periodic noise this waveform starts to repeat itself after a certain period. Can you hear that the periodic noise stimulus is periodic? Then you must have remembered a part of it in order to detect its reoccurrence.

We have studied the lifetime of auditory sensory memory, its susceptibility to interference and the capacity of the auditory sensory store using the pitch of sine tones and using periodic noise stimuli. We are presently replicating our findings with other random patterns such as periodic random sine tone patterns.

Kaernbach, C. (2004). The memory of noise. Experimental Psychology 51, 240-248.

Kaernbach, C., Schlemmer, K. (2008). The decay of pitch memory during rehearsal. Journal of the Acoustical Society of America 121, 1846-1849.

periodic noise

periodic sine tone pattern

 

Visual sensory memory

For the study of visual sensory memory we use visual pink noise stimuli. You might be surprised that these grayscale images are called pink. They are called so because their spatial frequencies decay in a specific way (1/f) emphasizing the lower frequencies. Light with an emphasis on lower light frequencies would look pink. This 1/f course of spatial frequencies is typical for natural images. Visual pink noise is a random stimulus as close as can be to natural stimuli.

Looking at these fuzzy stimuli you might think it should be impossible to remember them. We found that people can remember them quite well. They can recognize them easily even after one week.

Kaernbach, C., Bartsch, T., Schubert, A., Kanczok, J., Ulrich, A. M., Brütt, M. (2020). How similar is similar? A novel sensory memory task based on visual pink noise and its implications for pattern separation and completion. In preparation.

 

Visual pink noise

pink noise 1 pink noise 2 pink noise 3 pink noise 4