Color‐hierarchies in executive control of monkeys' behavior

Abstract

Processing advantages for particular colors (color-hierarchies) influence emotional regulation and cognitive functions in humans and manifest as an advantage of the red color, compared with the green color, in triggering response inhibition but not in response execution. It remains unknown how such color-hierarchies emerge in human cognition and whether they are the unique properties of human brain with advanced trichromatic vision. Dominant models propose that color-hierarchies are formed as experience-dependent learning that associates various colors with different human-made conventions and concepts (e.g., traffic lights). We hypothesized that if color-hierarchies modulate cognitive functions in trichromatic nonhuman primates, it would indicate a preserved neurobiological basis for such colorhierarchies. We trained six macaque monkeys to perform cognitive tasks that required behavioral control based on colored cues. Color-hierarchies significantly influenced monkeys' behavior and appeared as an advantage of the red color, compared to the green, in triggering response inhibition but not response execution. For all monkeys, the order of color-hierarchies, in response inhibition and also execution, was similar to that in humans. In addition, the cognitive effects of colorhierarchies were not limited to the trial in which the colored cues were encountered but also persisted in the following trials in which there was no colored cue on the visual scene. These findings suggest that color-hierarchies are not resulting from association of colors with human-made conventions and that simple processing advantage in retina or early visual pathways does not explain the cognitive effects of color-hierarchies. The discovery of color-hierarchies in cognitive repertoire of monkeys indicates that although the evolution of humans and monkeys diverged in about 25 million years ago, the color-hierarchies are evolutionary preserved, with the same order, in trichromatic primates and exert overarching effects on the executive control of behavior.

Color Modulates Feature Integration

“…There was also a slight advantage of terminating red flashes over other colors such as blue and green, as participants were more veridical in reporting their location as well. This small improvement in accuracy for red flashes in the terminating condition may arise from a stronger weight for red signals in stopping, as has been shown in studies investigating response inhibition (Blizzard et al, 2017;Ghasemian et al, 2021). The lack of significant differences between the other colors in the terminated condition may be due to the smaller magnitude of the perceptual shifts when the flash terminates the motion sequence.…”

The effect of cue utilization in driving on response inhibition

“…There was also no relationship evident between response inhibition and driving experience. Ghasemian et al (2021) showed that the effects of red on response inhibition as measured in the stop‐signal task is dependent on inherent neural circuitry. Thus, if red's effect on response inhibition is inherent and not due to an association created through man‐made inventions in driving (e.g., traffic lights, brake lights) where red corresponds to stop, this could explain the lack of driving status modulating performance, independent to cue utilization.…”

Dynamic modulation of inhibition ability following repeated exposures to morphine in macaque monkey

“…Inhibition ability (also known as response inhibition) is a key executive function which enables deliberate suppression of inappropriate actions, thoughts, and emotions. It has been examined by behavioral tools such as stop-signal paradigm (Ghasemian et al, 2021a;Mansouri et al, 2016Mansouri et al, , 2017aVerbruggen et al, 2019). In this paradigm, subjects deliver a speeded response in a primary task (Go trials), which is a simple or choice reaction time task, and withhold response in smaller proportion of trials (Stop trials).…”

“…Moreover, executive control is greatly dependent on prefrontal cortical regions (Aron et al, 2014;Mansouri et al, 2017bMansouri et al, , 2020aRoberts et al, 1998) which are different in terms of organization and cytoarchitecture between rodents and human (Petrides et al, 2012), whereas macaque monkeys are very closer to human in such respects (Mansouri et al, 2017b;Petrides et al, 2012;Roberts and Clarke, 2019). Moreover, a close homology exists between humans and macaque monkeys in the way that contextual factors affect their executive functions (Ghasemian et al, 2021a(Ghasemian et al, , 2021bMansouri et al, 2007Mansouri et al, , 2020aRoberts and Clarke, 2019). Therefore, macaque monkeys are suitable models for studying the time course of alterations in inhibition ability and providing more insights regarding the vulnerability of executive control in situations that resemble medical or recreational use of prescribed opioids in humans.…”

“…In this study, using two versions of stop-signal task (Ghasemian et al, 2021a(Ghasemian et al, , 2021b, we examined the time course of changes in inhibition ability before exposure, after initial exposure (early phase), and also after repeated exposures (late phase) to morphine (Figure 1). Also, we examined morphineinduced conditioned place preference (CPP) in monkeys at various stages of exposure to morphine.…”