Bottom-Up Processing
By Victoria Rousay, published Jan 21, 2021
Take-home Messages
- Bottom-up processing focuses on interpreting sensory information in real-time [Gibson, 1966].
- Bottom-up processing occurs as our sensory receptors receive new sensory information and does not require the use of prior knowledge or experiences.
- Bottom-up processing is data-driven and emphasize the importance of the stimulus itself, the raw data of the direct experience.
- Bottom-up processing would function in a series of events that began with the intake of new sensory information, then our sensory receptors sending signals to the brain, where the brain would then process these signals and finally construct a perception based off the signals that were received.
The bottom-up process involves information traveling 'up' from the stimuli, via the senses, to the brain which then interprets it, relatively passively. Bottom-up processing is also known as data-driven processing, because the processing of information begins with environmental stimuli, and perceptions are built from sensory input.
Bottom-Up vs. Top-Down Processing
How exactly do people process perceptual information from the world around them? There are two basic approaches to understanding how this sensation and perception takes place. One of these is known as bottom-up processing and the other is known as top-down processing.
Bottom-Up
Data driven
Focuses on incoming sensory data
Takes place in real time
Top-Down
Info is interpreted using contextual clues
Uses previous experience and expectations
Bottom-up processing can be defined as sensory analysis that begins at the entry-level—with what our senses can detect. This form of processing begins with sensory data and goes up to the brain's integration of this sensory information. Information is carried in one direction starting with the retina and proceeding to the visual cortex.
This process suggests that processing begins with a perception of the stimuli and is fueled by basic mechanisms developed through evolution. Unlike top-down processing, bottom-up processing is purely data-driven and requires no previous knowledge or learning. Bottom-up processing takes place as it happens.
For example, if you see animage of an individual letteron your screen, your eyes transmit the information to your brain, and your brain puts all of this information together.
HYPOTHESIS AND THEORY article
Front. Psychol., 17 May 2013 | //doi.org/10.3389/fpsyg.2013.00276
What is bottom-up and what is top-down in predictive coding?
Karsten Rauss1* and Gilles Pourtois2
- 1Institute of Medical Psychology and Behavioral Neurobiology, Faculty of Medicine, University of Tübingen, Tübingen, Germany
- 2Psychopathology and Affective Neuroscience Lab, Department of Experimental Clinical & Health Psychology, Ghent University, Ghent, Belgium
Everyone knows what bottom-up is, and how it is different from top-down. At least one is tempted to think so, given that both terms are ubiquitously used, but only rarely defined in the psychology and neuroscience literature. In this review, we highlight the problems and limitations of our current understanding of bottom-up and top-down processes, and we propose a reformulation of this distinction in terms of predictive coding.
Introduction
A central assumption in predictive-coding theories is that activity in the nervous system reflects a process of matching internally generated predictions to external stimulation [Heekeren et al., 2008; Bar, 2009]. Evidence for this assumption has been collected at different levels of neural processing [Rao and Ballard, 1999; Hosoya et al., 2005; Muckli et al., 2005; Summerfield et al., 2006; Alink et al., 2010], which suggests that predictive-coding operates across a wide range of spatial and temporal scales.
A second important assumption in predictive coding is that predictions are transferred from hierarchically higher levels of processing to lower ones, whereas signals traveling in the opposite direction encode prediction errors [Rao and Ballard, 1999; Serences, 2008; Friston, 2009; Grossberg, 2009]. In accordance with terminology commonly used in research on perception, it has thus been suggested that predictive signaling reflects top-down processes, whereas prediction-error signaling constitutes bottom-up processing [Friston, 2009; Alink et al., 2010; Hesselmann et al., 2010].
In this review, we argue that predictive coding provides a powerful conceptual framework that goes beyond the standard dichotomy of “bottom-up” and “top-down.” We first provide an overview of previous attempts at defining bottom-up and top-down processes, and we highlight their problems and limitations. We then outline how predictive coding offers a unique perspective for re-defining what is meant by these terms.
Throughout the remainder of this paper, we refer to ascending and descending connections when discussing the anatomy of biological systems or the architecture of artificial ones [Friston, 2005; Clark, in press]. Functional activity along these two types of connections is referred to as feedforward and feedback, respectively. We avoid additional terms such as “recurrent” or “reentrant,” because we believe they can be subsumed under “feedback” in most cases.