Using kinematics to perceive expectations and deception

Experiment 1 of Runeson & Frykholm (1983) established that an invisible source of influence could be perceived even when only the movement kinematics of an actor was present. Whether this perceived invisible source referred to the intention of or outcome achieved by the actor remains an empirical question. The subsequent experiments in this paper explicitly studied whether it was possible to perceive internal sources of influence via kinematics.

Experiment 2: Perception of weight expectations

Postural adjustments don't come only after an object is being lifted. Instead, they take effect even before one has come into contact with the object. These postural preadjustments typically depend on the actor's expectations of the object's weight. We see this everywhere in our daily lives. For instance, when we know an object is heavy, we tend to take precautionary measures prior to lifting so as to put ourselves in a biomechanically safe and advantageous position to effectively lift it. Note the emphasis on postural preadjustments that take place before the object is lifted. This was essentially what the second experiment explored.

Using kinematics to perceive 'invisible' causes

In a previous blog, we learnt from Runeson & Frykholm (1981) that the weight of a lifted object could be accurately perceived even when observers only had access to kinematic information (i.e., position, time, and the temporal derivatives of position). This was explained using the kinematic specification of dynamics (KSD) principle, where the kinematic information created by causal factors uniquely specifies those factors. This means that the perception of these causal factors is simply a matter of detecting the specifying kinematic information.

Kinematic specification of object weight

To illustrate this, let's look at the case of lifting an object. A lifted object, like a box, will have mass. Couple this with a gravitational field (like the one on Earth), and we get a downward force that's proportional to the object's mass (i.e., the object's weight). Once picked up, the weight of the object perturbs one's centre of mass such that to maintain balance (while still remaining energetically efficient), an individual will have to lean back proportionally to the object's weight. More specifically, humans typically do this by tilting their torsos backwards while pushing their pelvises forward. This creates an angle between the upper and lower parts of their bodies (this angle is 180° when standing straight without lifting any weight), an angle which varies systematically with object weight. Note how this fits into our definition of the KSD principle -- variation in kinematic information (backwards tilt / trunk-leg angle) is regulated by the causal dynamics (object weight) of the task. To complete the principle, it is hypothesised that this kinematic information then maps 1:1 to the dynamics that caused it in the first place.

Bermúdez (2023) Chapter 1.1: Behaviourism

The introduction of the book informed us about the components and goals of cognitive science. In this next chapter, Bermúdez takes us on a historical tour of the key developments across psychology, linguistics, and mathematical logic that preceded the establishment of cognitive science. Here, he focuses on four of these developments, namely those in behaviourism, algorithmic computation, linguistics, and information-processing models.

Incidentally, this is where Bermúdez explicitly places cognitive science in the information-processing tradition, asserting that "the guiding idea of cognitive science is that mental operations involve processing information, and hence, we can study how the mind works by studying how information is processed". As an ecological psychologist, I naturally disagree with this stance, but I reserve my judgment for now as I attempt to work through this material with an open mind.

That being said, this post will focus on behaviourism in psychology, and I'll come back to cover the rest of the mentioned developments in due time. Here, we'll look at what behaviourism is and the key studies that led to its eventual rejection in psychology.

Visual perception of lifted weight

Is it possible to visually perceive the weight of an object? Intuitively, this does not seem possible. After all, what an object looks like tells you nothing reliably about what it is made of. It is only by attempting to carry or lift an object can one determine its weight or mass. It would hence seem that knowledge of object weight is one that is reserved only for the haptic, and not the visual, system.

The research

Runeson & Frykholm (1981) argue otherwise. Object weight CAN be visually perceived! In this paper, they define the study of motion in two ways. Firstly, motion and its changes can be accounted for descriptively. This is done by studying kinematic variables, defined as those of position, time, and the temporal derivatives of position (e.g., velocity, acceleration). Given that any real-world task of interest to psychologists typically involves human behaviour (and this entails some sort of motion), studying kinematics is a good starting point to describe the motions and changes in motion involved. However, kinematics are purely descriptive -- they tell you nothing about what caused those motions and their changes. To account for this, we need to study the dynamics of a task, which deals with kinematic variables plus mass, hence allowing scientists access to the different forces involved in the subsequent kinematic patterns observed.

Bermúdez (2023) Introduction: The Challenge of Cognitive Science

What is Cognitive Science?

Cognitive Science describes the interdisciplinary study of human cognition. These disciplines include psychology, philosophy, neuroscience, computer science, linguistics, and anthropology (See Fig. 1). The main idea here is that each of these disciplines brings about its own tools, techniques, and perspectives, and while each is necessary, they are by themselves insufficient for a complete picture of human cognition.

Fig. 1 Core disciplines of Cognitive Science (Sloan report 1978, see Gardner (1985))

Cognitive Science Book Club!

I was first introduced to Cognitive Science during the 2nd year of my undergraduate degree. At that point in time, I was neck-deep in the sport psychology literature and didn't pay much heed to the exact details of my cogsci module. It was only later on, after being introduced to J.J. Gibson's Ecological Psychology, did I come to fully appreciate the interdisciplinary nature of studying human cognition and behaviour. To a certain extent, I'd identify myself as an ecologically-oriented student of cognitive science. Funnily enough, that cognitive science module was where I first encountered Gibson AND Helmholtz, the funny part being that their work on optic flow and outflow respectively were combined to explain vection (the experience of self-motion when one is, in reality, not moving).

Initial thoughts on dynamical systems

Here's another essay I wrote during my one-month stint at Leeds Beckett University, this time on dynamical systems. Admittedly, this is an area I really lack confidence in. Ecological Psychology has been great, but there's something about the mathematical nature of dynamical systems that catches me off guard. Nothing ever comes easy though, so hopefully this essay kick-starts my more intentional exploration into all things dynamical!

 

Introduction

Dynamical systems theory is widely seen as the appropriate methodological tool to study not just Ecological Psychology, but other areas of the study of human behaviour, including social and clinical psychology, as well as neuroscience. But what are dynamical systems? And why might there be a need for them? In this essay, I answer these questions in an attempt to consolidate my infant knowledge on this topic.

Some initial thoughts on affordances

This summer, I had the pleasure of studying under Andrew Wilson at Leeds Beckett University. I really respect Andrew's work (check out his blog https://psychsciencenotes.blogspot.com/), and alongside his PhD supervisor Geoffrey Bingham, their research and approach have really shaped my thoughts on how we should tackle the problem of understanding human behaviour. Two weeks into my time at LBU, Andrew got me to write an essay on the concept of affordances in Ecological Psychology. Keep in mind that this essay wasn't written with the blog in mind (I only started the blog a week later) and was instead written with the purpose of organising my thoughts on affordances. Naturally, there may be parts that seem to assume knowledge on the part of the reader, but I thought it'd be better to get the ball rolling and post the original draft rather than rewriting it. So here we are!

Introduction
 
The concept of affordances plays a central role in Ecological Psychology theory. But what exactly are affordances? Why do we need them in the first place? How do they help us perceive and act? And how do scientists go about studying affordances? These are some of the questions that I will be attempting to answer, as I wrap my head around and try to articulate the complex nature of affordances.