Feb. 02, 2016
 

It started like any other day in the lab. Dr. Noga Cohen and Dr. Tali Leibovich, then PhD candidates in Prof. Avishai Henik's Cognitive Neuropsychology Lab, noticed a spider crawling on Tali's desk. Tali was afraid of spiders and that's why she asked Noga to "take care" of the spider. Noga, on the other hand, couldn't understand what Tali was afraid of. Noga claimed that the spider was small. Tali insisted that the spider was big. How could it be, if they both saw the exact same spider? 

To answer that question, they designed an experiment, the results of which were published in the journal Biological Psychology recently. To conduct their study, Noga and Tali invited female students to fill out a questionnaire that measured fear of spiders and divided the participants into two groups based on their fear-of-spiders level (afraid and not afraid). Then, the participants were asked (1) to estimate the real world size of spiders and other animals (presented in pictures) relative to a fly and a rabbit, and (2) to report the unpleasantness each picture made them feel. 

The results revealed that participants who were afraid of spiders estimated spider size to be larger compared with participants who weren't afraid of spiders. In contrast, the size of other animals such as wasps and butterflies were ranked similarly by both groups. Further analyses showed that size estimation was affected by both the level of unpleasantness and how relevant the animal was to the participant (spiders are relevant to those who are afraid of them). 

So who was right? Noga or Tali? It turns out that they were both right. This study shows how perception of even a basic feature like size is influenced by emotion, and demonstrates how each of us experience the world in a unique and different way. This study also brings up more questions such as: Is it fear that triggers size disturbance, or maybe the size disturbance is what causes fear in the first place?Future studies that attempt to answer such questions can be used as a basis for developing treatments for different phobias.  

Spiders.jpg
Left – Example of a trial in the study. Participants were asked to place the arrow on the line according to the size of the spider relative to a fly and a rabbit.  

Right – Results: participants who were afraid of spiders rated only spiders as being significantly larger than other stimuli compared with participants who were not afraid of spiders.