Scene Identification and Emotional Response: Which Spatial Frequencies Are Critical?

Abstract

Emotional responses are regulated by basic motivational systems (appetitive and defensive), which allow for adaptive behavior when opportunities and threats are detected. It has been suggested that specific ranges of spatial frequencies of the visual input may contain information that is diagnostic for discriminating emotionally relevant from less relevant contents, and that specialized neural modules may analyze these spatial frequencies to allow efficient detection and response to life-threatening or life-sustaining stimuli. However, there is no evidence supporting this possibility regarding natural scenes, which are highly varied in terms of pictorial composition. The present study examines how low and high spatial frequency filtering affects the understanding of natural scene contents and modulates the amplitude of the late positive potential (LPP), a well-known component of the event-related potentials that reflects motivational significance. The content of an initially degraded (low-or high-passed) picture was progressively revealed in a sequence of steps by adding high or low spatial frequencies. At each step, human participants reported whether they identified the gist of the image. The results showed that the affective modulation of the LPP varied with picture identification similarly for low-passed and high-passed pictures. The engagement of corticolimbic appetitive and defensive systems, reflected in the LPP affective modulation, varied with picture identification, and did not critically or preferentially depend on either low or high spatial frequencies.

Electrocortical amplification for emotionally arousing natural scenes: The contribution of luminance and chromatic visual channels

“…One might therefore expect less sensitivity to variation in the physical composition of emotionally arousing pictures. In this respect, the insensitivity of the LPP to the specific visual channel through which the emotional image is conveyed replicates previous studies finding that this ERP component is relatively immune to low level physical characteristics such as physical composition (Bradley et al, 2007, De Cesarei & Codispoti, 2011) and stimulus size -- a proxy for viewing distance (De Cesarei & Codispoti, 2006).…”

“…First, a blurred grayscale version of each picture was created and filtered with a 2-dimensional low-pass average filter, set to increasingly attenuate spatial frequencies above 1 cycles per degree (cpd) using a square average kernel of 12 pixels. As illustrated in the spatial spectrum in Figure 1B, this leads to substantial reduction of contrast energy at frequencies above 3–4 cpd, which allows accurate identification of picture content (De Cesarei & Codispoti, 2011), while still primarily yielding low spatial frequency signals (Loftus & Harley, 2005). A negative image was then created from this picture by subtracting the mean gray value, multiplying by −1 and then rescaling to the original gray value range.…”

“…Initial studies with pictures of scenes or faces have suggested that early sensory amplification for emotional stimuli largely depends on the brain’s ability to extract coarse information from low spatial frequency and luminance channels (Pourtois, Dan, Grandjean, Sander, & Vuilleumier, 2005). However, other studies examining late neuroelectrical correlates of higher-order emotion processing have failed to find evidence that emotional modulation of cortical activity is preferentially affected by low spatial frequencies (Bradley, Hamby, Low, & Lang, 2007; De Cesarei & Codispoti, 2011). In contrast, selective engagement of chromatic mechanisms, which under ideal conditions (e.g., using high spatial frequencies) may bias the processing towards parvocellular pathways, has been less consistently implicated in emotional facilitation of sensory processing (e.g., Pourtois et al, 2005).…”

“…For example, the late positive potential (LPP), a centro-parietal evoked component that is most consistently modulated by hedonic content (Cuthbert, Schupp, Bradley, Birbaumer, & Lang, 2000; Schupp et al, 2000), appears to be immune to the image’s physical properties, provided that individuals are able to categorize the stimuli (De Cesarei & Codispoti, 2011, 2013). Although the neurobiological mechanisms that give rise to the LPP remain to be explored more extensively, the existing evidence suggests that this component is generated and sustained by a very broadly distributed network of cortical and subcortical structures including many that lie outside of traditional sensory areas (Liu, Huang, McGinnis-Deweese, Keil, & Ding, 2012; Sabatinelli, Keil, Frank, & Lang, 2013; Sabatinelli, Lang, Keil, & Bradley, 2007).…”

Early Spatial Frequency Processing of Natural Images: An ERP Study

“…Participants had no previous experience with the materials used in this experiment. In a previous study, data from the present dataset were analyzed in a later time interval to investigate the role of spatial frequencies and identification on a well-established ERP component of emotional modulation, namely the Late Positive Potential (LPP) [18].…”