\end{scope}
%lens
\begin{scope}[yshift=16mm]
- \filldraw[draw=black, fill=white, thick] (75,10) circle (12);
- \clip (75,10) circle (12);
+ \filldraw[draw=black, fill=white, thick] (80,10) circle (12);
+ \clip (80,10) circle (12);
\draw[dotted, step=3] (0,0) grid (90,30);
\sqsignal{15}{9}{3}{10}{0.6mm}{cellred}
\end{scope}
\end{tikzpicture}
\tikzexternaldisable
- \caption[vibrotactile circuit and signal.]{On the left: electrical diagram for driving the actuators. Two signals, one for Frequency and the other for Amplitude are modulated. On the right: a low-frequency signal with 50\% duty cycle for Frequency, a high-frequency signal with an adjustable duty cycle for Amplitude, and the modulation of both signals.}
+ \caption[vibrotactile circuit and signal.]{On the left: electrical diagram for driving the actuators. Two signals, one for Frequency and the other for Amplitude are modulated. On the right: a low-frequency signal with 50\% duty cycle for Frequency, a high-frequency signal with an adjustable duty cycle for Amplitude ($\frac{3}{4}$ in this example), and the modulation of both signals to drive the actuator.}
\label{fig:actuatorcircuit}
\end{figure}
The idea is essentially that the perception we have of environment is not just based on a bunch of input stream from our senses.
It is the integration of these input streams with the exploratory movement that we made, with our memories and experience.
This is because the input streams depend on the exploratory movements, and we make these exploratory movement to seek for information and match it with our previous knowledge to shape our perception.
+
The nature of the movement itself, that Lederman and Klatzky call exploratory procedures~\cite{lederman87,lederman96}, enables people to sense different properties of objects.
For exemple with a lateral motion we can feel the texture of an object, and with a pressure we can feel its hardness.
When we enclose an object with our hands we cans sense its volume and global shape, but if we follow its contours with our fingers we can not only sense its global but also exact shape.
For example sensory substitution consists in translating information that is typically sensed with one sense to another sense~\cite{bachyrita72}.
Several sensory substitution devices use the sense of touch with active exploration gestures to replace vision \cite{collins73,linvill66,bliss70,gapenne03}.
They typically enable blind people to read printed books, or scan their environment with a haptic white cane.
-Without active exploration, our brain cannot process such a tactile input stream.
+Without active exploration, our brain cannot process such a complex tactile input stream.
Gibson's theory involves a close relation between the animal (humans in our case) and its environment.
Gibson makes a difference between the physical world and the environment.
There is a central stage representing the goal the person would like to reach, and three stages for the execution of actions and the evaluation of the changes on the world.
Norman uses this model to explain the many usability issues that can arise when this mental model differs from the \defword{conceptual model} of how this object actually works.
+\input{figures/sevenstages.tex}
+
Norman also participated to the introduction of the concept of affordance to the HCI community.
Contrary to objects found in the nature, human-made objects can leverage our knowledge about human characteristics.
-We can reduce tha gaps between mental model and conceptual model by creating affordances.
+We can reduce the gaps between mental model and conceptual model by creating affordances.
Norman gives the example of doors designed in a way we know which side to pull and which side to push~\cite{norman88}.
The pull side has a handle that affords grasping and pulling whereas the push side has a flat plate that affords pushing.
However we cannot control all the physical properties of all the objects around us.
He also describes hidden affordances, and false affordances.
Because of this, Norman makes a distinction between an affordance, as a property, and a \defword{signifier} which is a perceivable properties that advertises the existance of an affordance~\cite{norman02}.
-\input{figures/sevenstages.tex}
-
%Perception/action cycle~\cite{gibson79}
%Sensorimotor loop~\cite{oregan01a}
%It is also used in other contexts like surgery, in which vision is required for a primary task, and haptics is used to replace vision at a different scale and point of view~\cite{robineau07}.
-
-Human processor: perceptual system, motor system, cognitive system~\cite{card83}
+There are other practical models in HCI literature that guide the design of interaction techniques and interactive devices.
+One of the most universal mathematical models in interaction is certainly Fitts' law that measures the difficulty ($ID$) of a target selection movement $ID=\log_2\left(\frac{2D}{W}\right)$~\cite{fitts54}.
+The model says that the longer the distance and the smallest the target width, the higher the difficulty.
+With the original experiment protocol, participants perform a reciprocal left-to-right movement between two targets of width $W$ and distance $D$ (also called movement amplitude).
+The reciprocal aspect of the task reduces visual search, hence the influence of perception.
+Therefore this is essentially a measure of motor performance.
+This is an active research topic with new contributions every year for decades.
+HCI research usually uses MacKenzie's throughput-based formulation \cite{mackenzie92}, and experimental protocols were adapted to 2D \cite{mackenzie92a}, 3D \cite{murata01}, and similar tasks like steering~\cite{accot97}.
+%ballistic\cite{meyer88}
+
+Besides motor-behavior models, we discussed perceptual empirical evaluations and models in \refchap{chap:output}.
+GOMS models are examples of human behavior model that takes into account both perception and actions.
+They model humans with three components: a perceptual system, a motor system, and a cognitive system~\cite{card83}.
+These are therefore more generic than models such as Fitts', they model a greater diversity of behavior.
+In particular the Keystroke-Level Model (KLM) defines several types of perations from mental activities to key presses~\cite{card80}.
+Typically it leverage models such as Fitts' to quantify pointing operations.
+With these models we can describe interaction techniques as sequences of atomic operations, and predict average performance based on empirically-defined rules.
+
+The models we discussed take into account human behavior, and to some extent the way interaction techniques work, but not necessarily how they are implemented.
+For example they do not take into account the transfer function between the pointing device and the cursor.
+They do not necessarily take into account the integration or separation of degrees of freedom~\cite{mackinlay90}, or the type of feedforward~\cite{vermeulen13}.
+In my opinion thus is a limitation for the generative aspect of these models, and I believe we must include more knowledge about the implementation into interaction models.
+
+%Human processor: ~ : KLM
\subsection{System architectures and paradigms}
projects / hdr.git / commitdiff