Relationship between motion VEP and perceived velocity of gratings: effects of stimulus speed and motion adaptation

The N200 amplitude of the motion-onset VEP evoked by a parafoveal grating of variable speed (0.25–13.5°/s), constant spatial frequency (2 cpd), contrast (4%), and direction (horizontally rightward) was studied before and after adaptation to a stationary or drifting grating (1 or 4°/s). Psychophysical measurements were made simultaneously of the perceived speed. In the unadapted condition the slope of the N200 amplitude versus speed function is positive, but lower for high compared to low speeds. The N200 amplitude increases slightly after stationary adaptation. An increase in perceived speed is also evident after stationary adaptation. This increase is more pronounced for low compared to high speeds. Motion adaptation reduces N200 amplitudes over the entire speed range, whereas perceived speeds change from under-estimation to over-estimation when the speed exceeds 1.8°/s after 1°/s adaptation and 4.5°/s after 4°/s adaptation. The simultaneous evaluation of motion VEP and psychophysical results supports the view that the neurons generating the N200 component are also involved in speed perception. The data suggest the existence of a limited number (three or more) speed channels

Unsettling planning theory

Recent political developments in many parts of the world seem likely to exacerbate rather than ameliorate the planetary-scale challenges of social polarization, inequality and environmental change societies face. In this unconventional multi-authored essay, we therefore seek to explore some of the ways in which planning theory might respond to the deeply unsettling times we live in. Taking the multiple, suggestive possibilities of the theme of unsettlement as a starting point, we aim to create space for reflection and debate about the state of the discipline and practice of planning theory, questioning what it means to produce knowledge capable of acting on the world today. Drawing on exchanges at a workshop attended by a group of emerging scholars in Portland, Oregon in late 2016, the essay begins with an introduction section exploring the contemporary resonances of ‘unsettling’ in, of and for planning theory. This is followed by four, individually authored responses which each connect the idea of unsettlement to key challenges and possible future directions. We end by calling for a reflective practice of theorizing that accepts unsettlement but seeks to act knowingly and compassionately on the uneven terrain that it creates