perception additional reading

Question 1

Gibsons theory of direct perception strengths

Answer 1

• influence on modern approaches e..g robotics. Noe, 2004: argues that perception is a skilful activity resonating with Gibsons action oriented theory
• Norman, 1988: concept of affordances aligns with modern embodied cognition and supports the view that perception is tied to action. This idea influenced robotics and human-computer interaction

Question 2

Gibsons theory of perception limitations

Answer 2

• Chemero, 2003: concept of affordances lacks precision. unclear how affordances are perceived, and whether they are properties of the environment or the organism-environment relationship. Chemero (2003) attempted to reformulate affordances in a dynamic, relational way, but noted persistent ambiguity
• Pylyshyn (1999) criticized direct perception as incompatible with findings from vision science, such as visual illusions, which suggest interpretation. lacks emprical rigour compared to cognitive models

Question 3

radial outflow hypothesis strengths

Answer 3

• influence on robotics and autonomous systems: Srinivasan et al., 1991: showed that flying insects use optic flow to regulate speed and avoid collisions—real-world biological validation of the hypothesis. informed computational models and robotics. Algorithms inspired by optic flow are used for motion detection and navigation in artificial systems
• empirical support for heading detection via optic flow. Van de Berg, 1992: showed that radial flow patterns allow accurate heading estimation even in cluttered environments

Question 4

radial outflow hypothesis limitations

Answer 4

• Royden, Banks & Crowell, 1992: Gibson minimized the role of internal signals (e.g., proprioception, efference copy), but subsequent research shows these are crucial for disambiguating optic flow. found that when rotational components are present, humans rely on extra-retinal cues (like eye movement commands) to extract heading direction. This contradicts the idea of purely direct perception and supports a more integrative model involving cognitive processing
• While radial flow may suffice for simple, straight-line motion, it does not account for perception in curves, acceleration, or non-planar surfaces. Lappe, Bremmer, & van den Berg (1999) argued that curvilinear motion requires processing that goes beyond optic flow, involving predictive mechanisms and internal modeling. This criticism emphasizes that the radial outflow hypothesis, while useful, is incomplete as a general theory of motion perception

Question 5

affordances strengths

Answer 5

• By focusing on real-world interactions, affordances highlight how perception is tailored to environmental demands and organism-specific capacities. Norman (1988) popularized affordances in design, arguing that good design makes affordances visible, improving usability. For instance, a button affords pushing if it visually suggests that action
• Gibson’s affordances bridge the traditional gap between perception and motor behavior, suggesting that organisms perceive the world in terms of actionable possibilities rather than abstract properties (e.g., size, shape). This functional view has been influential in psychology, design, robotics, and human-computer interaction (Brooks, 1991)

Question 6

affordances limitation

Answer 6

• One of the most cited problems is that Gibson never precisely defined affordances, making the concept vague and difficult to operationalize. Chemero (2003) attempted to clarify this by defining affordances as relations, not properties. His radical embodied approach reframed them as dynamical organism-environment systems
• Norman 1999: Gibson claimed that affordances are directly perceived, but critics argue that in many situations, cognition, experience, or learning play a crucial role. Norman (1999) revised his view, stating that some affordances are perceived through learning or cultural experience (e.g., doors, icons), which contradicts Gibson’s notion of direct perception.

Question 7

planning and control systems strengths

Answer 7

• Desmurget & Grafton, 2000: The planning/control model explains differences in movement initiation vs. correction. In sports, for instance, an athlete may plan a movement (e.g., kicking a ball) but adjust trajectory based on ball movement (online control).
• “Planning and control allow for efficient and adaptive motor behavior in dynamic environments”

Question 8

planning and control systems limitations

Answer 8

• oversimplification of visual processing: ritics argue that the planning/control distinction is too binary. Visual processing is often interactive, not strictly divided. Franz & Gegenfurtner (2008) showed that perceptual illusions can influence grasping more than the two-stream model predicts
• Planning and control are not strictly sequential; they often overlap dynamically during action. Scheidt et al. (2005) showed that even during movement execution, adjustments may involve planning-level changes, not just reflexive control. Real-time feedback may update the motor plan itself, blurring the distinction between the two systems