A growing body of literature suggests that associative learning like conditioning is influenced by personality dispositions [2,3]. Neuroticism seems to be consistently linked with enhanced aversive conditioning, the roles of traits like Conscientiousness in complex reinforcement schedules is yet to be explored [3]. In our study, it has been evident that impulsivity and compulsivity as a parameter of self-control significantly contributes in shaping the thoughts to purchase something [4]. In this context, the present study was designed to explore the interactions of these different personality dispositions in conditionability of buying behaviour. 

The consumer behavior is generally governed by a delicate tension between two internal systems: the "reflective" system of executive control and the "reactive" system of instant gratification. In light of this thought, buying habits exist on a fluid spectrum that stretches from impulsive urges to compulsive rituals, and is strongly associated with latent components characterized by neuroticism and conscientiousness [5]. Emerging evidence suggests that, neuroticism is associated with impulsivity and contributes to the development of binge eating [6].

Neuroticism reflects the emotional instability and negative affect and conscientiousness reflects the goal-directed behaviour and impulse control [7]. When high Neuroticism intersects with low Conscientiousness leading to lack of control necessary to manage one’s emotional volatility, and emerge as poorly planned behaviour- hallmark of impulsivity.

Individuals with high impulsivity are more likely to make spontaneous decision to buy based on the sensory appeal and convenience of the purchase, even if it has health adversity or they have financial constraints. It is evident from neuroimaging studies that, the Ventral Striatum (VS); the brain’s reward center and the Amygdala, which hyper-reacts to emotional cues associated with the purchase that is fast food while the mesolimbic pathway floods the system with dopamine, signaling the intense "pleasure" of immediate acquisition, a process known as positive reinforcement. Another point is, high impulsivity is associated with high neuroticism [6] and neuroticism being exhibited as heightened emotional reactivity often triggers emotional eating as maladaptive coping mechanism. Which could be the reason, the activation of reward center while receiving the cues get fuelled easily for the individuals with high impulsivity. Especially, when the high neuroticism is coupled with low conscientiousness the executive functions necessary for top-down inhibitory control gets compromised and results in diminished activity in Prefrontal Cortex (PFC) to act as the voice of reason necessary to suppress the sudden urge [8,9].  Verplanken and Herabadi [10] describe this as "Temporal Myopia”, which is a form of cognitive nearsightedness where the brain being focused on the immediate reward loses the ability to see future consequences.

Compulsivity is defined as the tendency to perform repetitive, ritualized behaviours to alleviate internal tension or achieve a sense of satisfaction [11]. According to Costa and McCrae [7], individuals scoring high in Conscientiousness spectrum may exhibit a rigidity in adhering to rules, where following the rules becomes compulsory even if it lacks its necessity. In that aspect, compulsivity of doing the ritualistic behaviour can be related with conscientiousness to be rule bound.  Research indicates that when this high conscientiousness is coupled with low neuroticism, it allows to maintain the disciplined execution of repetitive tasks.

Now, when compulsivity is linked with buying behaviour, a form of conditioning, it is evident that, the compulsive buyer is often trapped in a "top-down" but inflexible behavioral loop. The neurobiology of the purchase in this case shifts from the goal-directed Ventral Striatum to the Dorsal Striatum, the region of deep-seated habits [12].  Unlike compulsivity represents with a failure of top-down cognitive control to inhibit deeply ingrained habits [13]. In this context, frequent exposure to highly palatable "fast foods", indulging impulsive urges can turn the behaviour into a compulsive behaviour. This transition is mediated by a critical neuroanatomical shift from the goal-oriented ventral striatum (nucleus accumbens) to the habit-centered dorsal striatum [14]. It is a shift from the "spark of joy" in the pleasure centers to the "autopilot" of habit. The continuous chasing of impulsive urge, to attain the temporary high of a spontaneous purchase, the behavior over time, carves a permanent path in the brain, turning a choice into a routine. It is necessarily looking for a thrill; you are simply caught in a rigid loop that you feel you must follow, no matter what.

The present study aims to explore the neurocognitive natures of specific interaction of impulsivity and compulsivity with neuroticism and conscientiousness in shaping the conditionability.

Participants

Participants aged between 18-25 years from middle-class socio-economic status females and males, non-obese normal weight as per the norm of Body Mass Index (BMI) rate [1] were recruited in the present study. Purposive sampling was used to recruit participants.  Participants were recruited with pre-screen measures such as information schedule, socio-economic status (SES) scale by Kuppuswamy, from the urban and semi-urban areas of West Bengal. To protect the integrity of the cognitive data, individuals with a history of psychological or physical distress, or those with vision impairments, were excluded. Prior to the study, informed consent was obtained from each participant, ensuring their awareness of the voluntary nature of the research.

Table 1: Demographic Details of participants.

Procedure

In the first step, an impulsive-compulsive checklist for fast food buying behaviour based on the themes found in our study [4] were constructed by Nonparametric Receiver Operating Curve (ROC Analysis by trapezoidal rule. It is administered to 100 participants to find out the optimal cut-off points to discriminate impulsivity from compulsivity, high from low impulsivity and high from low compulsivity. Following are the cut-off points for scoring norm in the checklist with scoring categories (Table 2) and the items (Table 3).

Figure 2 ROC Curve of the domains of the checklist of Impulsivity-Compulsivity.

Figure 1: ROC curve of different level of impulsivity and compulsivity where sensitivity of the checklist.

Figure 1 depicts the ROC curve of different level of impulsivity and compulsivity where sensitivity of the checklist for classifying the groups is more than average.

Table 2: ROC Analysis.

Note: The value less than the cut off values will be categorized as Compulsivity for Impulsivity-Compulsivity domain, Low Impulsive for High-Low Impulsivity domain and Low Compulsive for High-Low Compulsivity domain.

Table 2 depicts the cut off points for all the domains to categorize each domain are found to be significant in effectively classifying the groups. It indicates that the chances of categorizing different groups of impulsivity and compulsivity in the above domains by the checklist among the age group of 18-25 years is more than average in terms of probability.

Table 3: Domains and items of the checklist.

Note: I- Impulsivity, C- compulsivity.

The study employed a between-subjects matched-group research design. After constructing the Impulsivity and compulsivity checklist, it was administered to 40 participants along with Revised NEO Personality Inventory (NEO-PI-R; [7]). Participants were categorized into two distinct experimental groups (n = 20 per group) based on their personality profiles. However, they were classified into two groups by providing special emphasis on the nature of interaction of specific domains of personality from NEO-PI-R and the constructed checklist in shaping conditionability as evident from literature [5,6]. Based on these literature [5,6], a separate chi-square analysis was also conducted to test the following associations of Impulsivity, Compulsivity with Neuroticism and Conscientiousness.

Table 4: Chi-Square Test for association between Impulsivity, Compulsivity with Neuroticism and Conscientiouness.

Table 4 depicts the association between high and low level of impulsivity, compuslvity with high and low level of Neuroticism and Conscientiouness which is found to be significant. From the test of association, the groups of participants are classified as following:

High Impulsive Low Compulsive: High Neuroticism and Low Conscientiousness.

High Compulsive Low Impulsive: Low Neuroticism and High Conscientiousness.

In this way participants were classified in two groups with these combinations. Now in the experiment, the experimental stimuli consisted of six images of popular fast foods. To ensure ecological validity and affective relevance, 15 experts evaluated those images using a bidirectional scale [15] to rate familiarity and favourability. Images identified as "mostly familiar" and "moderately favourable" were selected for the final task. These images were paired with positive promotional messages (e.g., "Taste the Joy") and presented in a counterbalanced manner to account for potential interaction effects between specific foods and messages. There were two phases as follows:

Encoding Phase: Participants were presented with the six target fast-food images accompanying by positive messages on a screen for 45 minutes. Based on expert ratings for optimal processing speed, each slide was displayed for exactly 2 seconds.

Recognition Phase: After the 30-minute interval, the recognition task was administered. Participants were presented with the original target images interspersed with "lure" items (similar but previously unseen fast-food pictures). Using a binary response category, participants were asked to identify the familiar stimuli: pressing the 'y' key for "yes" (seen before) and the 'n' key for "no" (new/unseen). In this way their conditionability was assessed by the recognition task.

A Signal Detection analysis using a Signal Detection Paradigm was conducted to examine the recognition memory performance for fast-food stimuli among participants. For each participant, Hits and Misses which are Correct and incorrect identifications of target stimuli and False Alarms and Correct Rejections which are errors and correct identifications regarding lure items were calculated. Then, Sensitivity (d'); an index of the participant's ability to discriminate between known stimuli from distractors and Specificity; the accuracy of rejecting lures were calculated.

Figure 2: Signal Detection Analysis of recognition task for the group of High Compulsivity Low Impulsivity: High Conscientiouness Low Neuroticism.

Figure 2 Probability Distribution for the High Compulsive Low Impulsive Cohort illustrates high sensitivity (d' = 2.03) and a liberal criterion (c = -0.69). For these groups of participants, the leftward shift of the criterion line (the dashed vertical) signifies that the participants adopt a low threshold for "Yes" responses to satisfy the perceived requirements of the task and avoid missing targets.

Figure 3: Signal Detection Analysis of recognition task for the group of High Impulsivity Low Compulsivity: High Neuroticism Low Consceintiousness.

Figure 3 depicts the Probability Distribution for the High Impulsive Low Compulsive Cohort (High N / Low C) in signal detection analysis. The calculated sensitivity index (d' = 2.03) indicates high discriminability between stimulus types from distractors. The vertical dashed line indicates the decision criterion (c = -0.69). The leftward placement of this criterion relative to the intersection point highlights a liberal response bias. For these groups of participants, the leftward shift of the criterion line (the dashed vertical) indicates that the participants adopt a low threshold for "Yes" responses to satisfy the perceived requirements of the task and avoid missing targets.

A comparative analysis of these distributions reveals that while both the Impulsive and Compulsive groups they both utilized a significantly lowered decision threshold, as indicated by the leftward positioning of the criterion line (c = -0.69), participants demonstrated a systematic tendency to discriminate ambiguous internal evidence as a 'Signal.'

Table 5: Mean Signal Detection Performance as a Function of Personality Profile.

Note: N-Neuroticism, C- Conscientiousness

As shown in Table 5, both the Impulsive and Compulsive groups demonstrated a high level of recognition sensitivity (d' = 2.03), indicating a robust cognitive ability to distinguish previously seen fast-food images from novel distractors. However, the decision-making strategy for both groups was characterized by a negative criterion value (c = -0.69). A negative criterion indicates   a liberal response bias. This indicates that participants in both groups have a tendency to respond "Yes" (identifying an item as "seen") even when the internal evidence for that stimulus was relatively weak.

The aim of the study was to explore the neurocognitive natures of specific interaction of impulsivity and compulsivity with neuroticism and conscientiousness in shaping the conditionability. In this regard, the empirical results of the signal detection analysis (Table 5) suggest a striking behavioural convergence. Both the High Impulsive (HI) Low Compulsive (LC) (High Neuroticism; HN, Low Conscientiousness; LCO) and High Compulsive (HC) Low Impulsive (LI) (Low Neuroticism; LN, High Conscientiousness; HCO) groups exhibited an identical liberal decision criterion (see Table 5). Their behavioural output on the recognition task is indistinguishable, however, the underlying neuropsychological mechanisms of this tendency of "yes-leaning" bias are fundamentally different. This resembles with equifinality, where different neural pathways result in the same behavioural outcome [16].

In the HILC group, the liberal bias is driven by heightened emotional reactivity toward the fast-food cues, as it is associated with High Neuroticism (N) [7] with an overactive amygdala. When it is coupled with the Low Conscientiousness (LCO) profile, it reflects a failure of the Prefrontal Cortex (PFC) to exert inhibitory control [13]. So, putting it altogether, when presented with fast-food stimuli, which act as high-incentive rewards; the Ventral Striatum (VS) gets activated and triggers an immediate "approach" to have the fast food. Participants failed to execute inhibitory control on this urge due to LCO as the part of their personality disposition. As a result of which, they failed to filter out noise (lures), leading to a high rate of False Alarms. Their liberal bias emerged as an unfiltered reaction to the emotional and rewarding salience of the food imagery. In light of this conversation, it could be explained that they responded "Yes" not because they are certain, but because they lack the cognitive oversight to say "No" to a rewarding cue.

In contrast, the liberal bias in the HCLI group is rooted in the Dorsal Striatum (DS) and the Anterior Cingulate Cortex (ACC), which is responsible for habit formation and conflict monitoring [17]. These group of participants with high Consceintiousness, succumbed to their tendency to be excessively rule bounded. In this case, the liberal bias depicted in Table 5 does not stem from a lack of control, but from a rigid adherence to a stimulus-response loop. Once the fast-food stimuli are encoded as a target during the encoding phase, the partcicipants with high Consceintiouness (HCO) evaluated the recognition task as a rigid rule-following exercise. Consequently, they may over-apply the target category to similar-looking lures to ensure they don't miss any targets. Their liberal bias is a habitual over-inclusion to complete the goal rather than an emotional outburst.

While the SDT curve shows the same shift to the left (Figure 2 and 3), the nature of the error differs qualitatively: Impulsive Bias: A "Hot" process driven by dopamine-fueled urgency and a failure to suppress the "Yes" response is generally contributed by an imbalance in Prefrontal Cortex to inhibit the urge and ventral striatum to immediate approach to reward, the fast food On the other hand, Compulsive Bias is  a "Cold" process, which is not an emotional outburst and  is driven by an over-active habit system and a rigid focus on the signal, leading to the accidental inclusion of noise [18].

Figure 4: Neurocognitive mechanisms in Impulsivity and Compulsivity.

Figure 4 depicts neuroanatomy of behaviour while processing cues from food. There are Two centers of brain, one is homeostatic center, which receives metabolic and visceral feedbacks from hypothalamus and brain (highlighted with red) and send the signal through the other center hedonic center; thalamus, insula, cingulate gyrus to the areas of cognitive control for integration of hedonic and homeostatic information for general food intake. However, in impulsive behaviour, emotional cues from food stimulate the limbic system (thalamus, cingulate gyrus, insula), which then activates the reward system (ventral striatum and amygdala). The brain detects reward from food signals, and in the absence of hunger, the mesolimbic and mesocortical pathways result in a preference for immediate gratification from the pleasure of food cues [19-21]. In compulsive behaviour, the dorsal striatum region for habit formation becomes activated over time as a result of getting cues from fast food and repeating the same experiences. Top-down information control is activated, and formerly impulsive activity becomes compulsive behaviour.

This distinction is critical for understanding buying behavior. An impulsive buyer might purchase fast food due to a sudden, emotional craving they cannot stop. A compulsive buyer might purchase it because it has become a rigid part of their routine or a "rule" making them equally likely to "detect" the food cue in their environment.

1. Nuttall FQ. Body mass index. Nutrition Today. 2015; 50: 117-128.
2. Vul E, Harris C, Winkielman P, Pashler H. Puzzlingly high correlations in fMRI studies of emotion, personality, and social cognition. Perspectives on Psychological Science. 2009; 4: 274-290.
3. Haig BD. The role of individual differences in conditioning: A review of modern perspectives. J Behavioral Sciences. 2019; 44: 112-125.
4. Nag M, et. al. Eating behaviour from the perspective of fast food in-takers (In Print). Int J Social Sciences Review. 2025.
5. Kotov R, Krueger RF, Watson D, Achenbach TM, Althoff RR, Bagby RM, et al. The Hierarchical Taxonomy of Psychopathology (HiTOP): A dimensional alternative to traditional nosologies. J Abnormal Psychology. 2017; 126: 454-477. (Foundational for understanding latent personality components).
6. Lee-Winn AE, Townsend L, Reinblatt SP, Mendelson T. Associations of Neuroticism and Impulsivity with Binge Eating in a Nationally Representative Sample of Adolescents in the United States. Pers Individ Dif. 2016; 90: 66-72.
7. Costa PT Jr., McCrae RR. Revised NEO Personality Inventory (NEO PI-R) and NEO Five-Factor Inventory (NEO-FFI): Professional manual. Psychological Assessment Resources. 1992.
8. Billieux J, Rochat L, Rebetez MML, Van der Linden M. Are all facets of impulsivity related to self-reported compulsive buying?. Personality and Individual Differences. 2008; 44: 1432-1442.
9. Heatherton TF, Wagner DD. Cognitive neuroscience of self-regulation failure. Trends in Cognitive Sciences. 2011; 15: 132-139.
10. Verplanken B, Herabadi A. Individual differences in impulse buying tendency: Feeling and thinking. European J Personality. 2001; 15: S71-S83.
11. Fineberg NA, Chamberlain SR, Goudriaan AE, Stein DJ, Vanderschuren LJ, Gillan CM. New developments in human neurobiology of obsessive-compulsive disorder. CNS Spectrums. 2014; 19: 69-89.
12. Everitt BJ, Robbins TW. Neural systems of reinforcement for drug addiction: from actions to habits to compulsion. Nature Neuroscience. 2005; 8: 1481-1489.
13. Dalley JW, Everitt BJ, Robbins TW. Impulsivity, compulsivity, and top-down cognitive control. Neuron. 2011; 69: 680-694.
14. Everitt BJ, Robbins TW. Drug addiction: Updating actions to habits to compulsions ten years on. Annual Review of Psychology. 2016; 67: 23-50.
15. Aiken LR. Three coefficients for analyzing the reliability and validity of ratings. Educational and Psychological Measurement. 1985; 45: 131-142.
16. Cicchetti D, Rogosch VG. Equifinality and multifinality in developmental psychopathology. Development and Psychopathology. 1996; 8: 597-600.
17. Robbins TW, Gillan CM, Smith DG, De Wit S, Ersche KD. Neurocognitive endophenotypes of impulsivity and compulsivity: Towards dimensional psychiatry. Trends in Cognitive Sciences. 2012; 16: 81-91.
18. Wilson MJ, Vassileva J. Neurocognitive and psychiatric dimensions of hot, but not cool, impulsivity predict HIV sexual risk behaviors among drug users in protracted abstinence. Am J Drug Alcohol Abuse. 2016; 42: 231-241.
19. Campos A, Port JD, Acosta A. Integrative Hedonic and Homeostatic Food Intake Regulation by the Central Nervous System: Insights from Neuroimaging. Brain Sciences. 2022; 12: 431.
20. Likes, loops, and limbic systems: Unveiling the neurological impact of social media | by neurotechx content lab | neurotechx content lab | medium.
21. Saleem SM. Modified Kuppuswamy socioeconomic services scale, updated for the year 2020. Indian J Forensic and Community Medicine. 2020; 7: 1-3.