Researchers in France (Roux-Sibilon, Kalénine, Pichat & Peyrin, 2018) did an experiment which tested Paired Object Affordance with specific brain regions. In psychology, ‘affordance’ is basically a word for how one can recognize and interact with objects in your environment. For example, trees can be used for animals to climb to safety; twigs can be used to pick food out of monkeys’ teeth, etc. Paired-object affordance can be described as the next step up, in which the way an object in an environment interacts with another object in the environment (A key in a lock, a pencil and a paper, etc).
The study is attempting to see the role that two areas of the brain have on paired object affordance: The Ventral Stream and the Dorsal Stream. The dorsal stream is the part of the brain that locates and identifies an object’s location in space, while the ventral stream identifies an object is what an object does. To put it simply, Ventral = “what”, Dorsal = “where”.
The study used 14 right-handed participants, mainly in their twenties, with a 50/50 male to female ratio. The participants had their brains measured using an fMRI (Functional Magnetic Resonance Imaging) machine, which looks like a giant doughnut that has a bed in the middle, with the head section positioned in the hole, so they can get their brains scanned to see which parts were most active. The study used a test called the Paired Object Affordance task (POA), in which two objects were shown on screen. The flashing images one being standard position or mirrored (for example, if the paired objects were a pen and paper, then the pen would be in right hand for standard; left hand for mirrored. The object in the dominant hand was on dominant side for standard. Likely the reason for choosing solely right handed participants. 50% of the objects shared a theme of being in a kitchen context. The objects were asked to be identified on two grounds: one being Action and the other being Contextual. Action is identifying whether or not the two objects used could interact with each other, while the contextual portion asks if the images flashed on screen are objects used in the kitchen.
The entire process was interesting and somewhat like a game: The participants would be in the MRI machine, looking at a mirror which would show them pictures of the two items together for less than a second. In the participants’ right hand there were two keys they could push “Yes” or “No” to see if the picture shown matched the questions on whether the objects shown were action-based or contextual based.
What the scans revealed was that both the dorsal and ventral streams worked together when it came to doing this task. When it came to action, the dorsal stream’s sensorimotor areas (those which are linked to muscle movement) became most activated. The main part of the ventral stream, the lateral occipital complex, or LOC (which is used for more advanced object recognition, as well as comparing and contrasting), was also activated the most when it came to action-oriented tasks. It turned out that, for the more contextual-based tasks, different parts of the brain were used instead of the streams.
