Seeing Objects in Rhythms

How many impressions can our brain hold in mind at any moment? In fact, how long lasts one moment? And do we see and think in a continuous flow or in discrete steps? The research project Seeing objects in rhythms aims to shed light on these fundamental enigmas of human information processing. It has long been known that our brain has a very limited capacity for holding individual items in memory and can only process a small number of 3-4 objects. Sometimes, however, our mind seems to comprehend more. We can accurately calculate the average position from many objects at once, raising the question how the brain represents a group of objects when it can only track a few individual members. In fact, the research proposed here shows that our object processing capacity is not equally good at all times. Instead, we start with the observation that object memory fluctuates rhythmically over time. When seeing multiple objects, there are times, in which one can focus on more- and other times with fewer objects. Moreover, we find that these rhythms are faster when one tracks each individual object and slower for the object average. This leads to our core hypothesis: Objects are not continuously tracked but rhythmically sampled, and capacity limits root in the speed of the sampling rhythm. Slower sampling provides longer time windows to encode more objects, while faster sampling leaves less time in each cycle, resulting in capacity limits. Centered on these observations in our participants behavior, we formulate a theoretical model for object processing based on discrete, periodic sampling cycles. In this research project, we now test the scientific predictions resulting from this model for human brain activity. In order to track brain activity with high temporal resolution, we will use magneto-encephalography, which captures magnetic field changes on the head surface. Its combination with magnetic resonance imaging provides sufficient detail about the exact brain location. This will yield the brain correlates of capacity limits and object sampling. In a second step, we will change each participants brain rhythms with alternating electric currents applied to his / her scalp during object processing and brain recording. By this, we will be able to make causal inferences about sampling rhythms for object capacity. Classically, object capacity is thought of a mental limit to the amount of processed information in our spatial (3-D) surrounding. But things around us move and change over time, and so do our mental and brain processes. The research proposed here links fluctuations in attention over time to object memory and shows that the brains information processing capacity roots in the rhythmic nature of brain processes.

How many impressions can our brain hold in mind at any moment? In fact, how long lasts one moment? And do we see and think in a continuous flow or in discrete steps? The research project "Seeing objects in rhythms" aims to shed light on these fundamental enigmas of human information processing. It has long been known that our brain has a very limited capacity for holding individual items in memory and can only process a small number of 3-4 objects. Sometimes, however, our mind seems to comprehend more. We can accurately calculate the average position from many objects at once, raising the question how the brain represents a group of objects when it can only track a few individual members. In fact, the research proposed here shows that our object processing capacity is not equally good at all times. Instead, we start with the observation that object memory fluctuates rhythmically over time. When seeing multiple objects, there are times, in which one can focus on more- and other times with fewer objects. Moreover, we find that these rhythms are faster when one tracks each individual object and slower for the object average. This leads to our core hypothesis: Objects are not continuously tracked but rhythmically sampled, and capacity limits root in the speed of the sampling rhythm. Slower sampling provides longer time windows to encode more objects, while faster sampling leaves less time in each cycle, resulting in capacity limits. Centered on these observations in our participant's behavior, we formulate a theoretical model for object processing based on discrete, periodic sampling cycles. In this research project, we tested the scientific predictions resulting from this model for human brain activity. In order to track brain activity with high temporal resolution, we used magneto-encephalography, which captures magnetic field changes on the head surface. Its combination with magnetic resonance imaging provides sufficient detail about the exact brain location. This yielded the brain correlates of capacity limits and object sampling. In a second step, we changed each participant's brain rhythms with magnetic stimulation applied to his / her scalp during object processing. By this, we were able to make causal inferences about sampling rhythms for object capacity. Classically, object capacity is thought of a mental limit to the amount of processed information in our spatial (3-D) surrounding. But things around us move and change over time, and so do our mental and brain processes. The research carried out here links fluctuations in attention over time to object memory and shows that the brain's information processing capacity roots in the rhythmic nature of brain processes.