1. Once again… WHAT DO YOU SEE?
Is the sum greater than its parts:
The effects of conceptual and perceptual gist on perception of an image or scene
Brande, Lauren1; Munc, Alec2; Bridgeman, Bruce1
1. University of California, Santa Cruz; 2. San Francisco State University
Methods
Results
Discussion
WHAT DO YOU SEE?
45 students rated 66 image pairs. Ratings were based on a double-anchored scale.
1 = completely dissimilar.
10 = exactly the same.
3 conditions: perceptual gist, conceptual gist, and overall image similarity.
Perceptual condition: 15 participants rated image pairs based on physical qualities (shapes, colors, etc.). Conceptual condition: 15 participants rated the same image pairs based on conceptual themes.
Overall similarity condition: 15 participants were not told what to base their ratings on, just to rate overall similarity of the two images.
Every participant saw all 66 image pairs.
15 pairs consisted of conceptually related objects (for example 2 different types of cleaning products) but perceptually different.
15 pairs consisted of 2 scenes that were perceptually related but conceptually different.
20 pairs of perceptually similar but conceptually dissimilar objects, such tweezers and a tuning fork.
16 pairs of perceptually similar but conceptually different scenes.
We predicted that perceptual gist would have a bigger impact on overall image similarity than conceptual gist, but our data showed otherwise. Perceptual gist and conceptual gist were both correlated with overall similarity, but due to diverse pair types in the image pair sets, SDs were high. Perceptual gist had nearly the same effect size (r=.490, p<.001) as conceptual gist (r=.482, p<.001) on overall image similarity, contrary to our hypothesis.
An analysis of only the images with the highest similarity ratings used the top 15 image pairs from each condition. We considered the top 15 ranks for each condition when assigning an image pair to a data set so that an image appeared only in one set of rankings. The conceptual condition had a higher average rating than the perceptual condition. These ratings were significantly different (t(14) = , p <.001)
Conceptual gist image pairs received higher similarity ratings than perceptual pairs, indicating that conceptually similar images are seen as more similar overall. Thus the idea or semantic category behind an image or scene plays a larger role in judged similarity. We found that the content or predicted content of a scene affects perceived “sameness.” Participants might have been more particular when given the instruction to focus on the appearance of the images rather than the object or scene as a whole. They could afford to be more critical in the perceptual condition because they had clear-cut things to look for in the pairs, whereas participants in the conceptual condition used their knowledge of the images to determine similarity.The results also had a large overlap.
Abstract
We sought to determine the relationship between overall image similarity and conceptual and perceptual gist. We predicted that perceptual gist would have a larger effect on image similarity, but we found that both types of gist predict image similarity. Conceptual gist has a larger effect. Participants rated 66 randomized image pairs on a 1-10 scale. There were 3 conditions: perceptual gist rating, conceptual gist rating, and overall similarity rating. Perceptual gist and conceptual gist both correlated with overall similarity, but due to variability in the image pair sets the standard deviation for each condition was high. Perceptual gist had nearly the same effect size as conceptual gist on overall image similarity, contrary to our hypothesis. A second analysis, using only top-rated images in each condition, revealed that conceptual gist image pairs received a significantly higher similarity rating than perceptual pairs.
Once again… WHAT DO YOU SEE?
Objectives
2 types of gist (Oliva, 2005)?
Conceptual - semantic meaning of a scene or object
Perceptual - physical properties of the scene or object.
No empirical evidence for the dichotomy.
Because of gist’s importance in recognition memory we need a solid understanding of what constitutes the gist of a scene.
We explore the effect of each type of gist on overall perception of an image or scene and to determine which type correlates more with overall image similarity.
References
Alvarez, G., Brady, T., Konkle, T., & Oliva, A. (2010). Scene memory is more detailed than you think: The role of categories in visual long-term memory. Psychological science, 21,
Oliva, A. (2005) Gist of the Scene. In the Encyclopedia of Neurobiology of Attention. L. Itti, G. Rees, and J.K. Tsotsos (Eds.), Elsevier, San Diego, CA (pages ).
Wolfe, J M. (1998). Visual memory: What do you know about what you saw?. Current biology, 8, R303-R304.
Acknowledgements
Thank you to Bruce Bridgeman for his support and help throughout this long and sometimes discouraging process, as well as to the University of California, Santa Cruz for providing the opportunity for our research to be completed (and access to their numerous undergraduates). Not to mention, thank you to anyone still reading our poster!