Chapter 1-10: Unconscious Processing, Inattentional Blindness, Subliminal Effects, and Pheromones

Inattentional Blindness

  • Concept and origin: Inattentional blindness dates back to 1998 with Mack and Rock's experiments described in their book on the phenomenon. They used a standard procedure: present a small cross briefly on a computer screen for several trials; an unexpected object (e.g., a brightly colored rectangle) appears along with the cross.
  • Key finding: Participants who were busy attending to the cross often failed to notice the unexpected object, even if it appeared in the center of their visual field. When attention was not diverted to the cross, the object was easily noticed.
  • Meaningful stimuli and attention: Mack and Rock found that people were more likely to notice their own name or happy faces when presented with the cross than stimuli that were not meaningful to them (e.g., an upside-down face or an unrelated name).
  • Demonstration in everyday life and replication: A famous replication included an illusion with basketball players and a gorilla (the video commonly cited as demonstrating inattentional blindness). Several researchers replicated Mack and Rock’s core finding, illustrating that inattentional blindness can occur when attention is heavily loaded on a task.
  • Real-world relevance: Aviation psychologist Christopher Wickens examined pilots in flight simulators using head-up displays (HUDs). With high visual attention demands, pilots often miss objects that suddenly appear in their field of vision (e.g., an airplane on the runway), even when such objects are important.
  • Tension with original findings: These aviation results suggest that when a highly salient, important stimulus appears, people may still miss it if their attention is occupied elsewhere, challenging a simple view that attention always enhances noticing of meaningful stimuli.
  • Open question: Are there stable individual differences in susceptibility to inattentional blindness? Do some people experience it more often than others?
  • Individual differences research trends: Laboratories are exploring whether working memory and intelligence relate to susceptibility to inattentional blindness. Mack (Mac) remains interested in whether intelligence correlates with reduced susceptibility. Current state: we cannot yet say whether inattentional blindness affects a fixed 30% of people or appears as a stable personality trait across individuals.
  • Key takeaway: Attentional load and stimulus meaning interact to determine what we notice; high demand on attention can lead to missing highly salient events unless they are within or draw attention to our focus.

Unconscious/Automatic Processing: Mere Exposure and Attitude Formation

  • Mere exposure effect: Simply perceiving a stimulus repeatedly increases its positivity, even without conscious awareness or intention. Repeated exposure to brands or songs can make us like them more.
  • Experimental design (mere exposure): Participants are divided into a control group and an experimental group. They view the same web page; the experimental group experiences occasional pop-up ads. One week later, both groups rate their attitude toward the product.
  • Findings: The experimental group exposed to the ad rated the product more favorably than the control group after one week and still showed differences after three months.
  • Exceptions: If the first exposure to a product is negative, subsequent attitudes are less likely to be positive.
  • Product placement and mirror exposure: Real-life examples show similar effects. Reese's Pieces in E.T. (1982) correlated with a 65% increase in Reese's sales. Transformers (2007) with a yellow Camaro correlated with a 10% increase in yellow Camaro sales. Mirror exposure effects can occur even when stimuli are subliminal or presented without conscious awareness.
  • Subliminal exposure and attitude: Subliminal mirror exposure can produce a positive attitude toward stimuli even when participants do not consciously remember being exposed to them.

Subliminal Messaging: Perception vs Persuasion

  • Popular misconception: Subliminal messages are thought to influence behavior without conscious awareness, often tied to the idea of manipulation by advertisers or governments.
  • Distinctions:
    • Subliminal perception: Stimuli are perceived outside conscious awareness but still processed by sensory systems.
    • Subliminal persuasion: Using that processing to motivate changes in thinking or behavior (e.g., buying a product).
  • Evidence and limits:
    • A 2006 study found that subliminal cues of Lipton tea increased the intention to drink Lipton tea, but only among participants who were actually thirsty. No direct behavior (purchase) was measured.
    • The motivation factor (thirst) mattered: only thirsty participants showed increased intention, suggesting that subliminal cues interact with internal states.
    • Caution: Intention measured in a lab does not guarantee actual future purchasing behavior; many factors influence real-world decisions.
  • Priming vs subliminal messaging:
    • Priming often uses supraliminal stimuli (perceived consciously) to influence subsequent thoughts or behaviors.
    • Classic priming demonstrations include mood-congruent effects and stereotype activation, which can alter performance or behavior under certain conditions.

Priming: Supraliminal Cues and Behavioral Effects

  • Concept: Priming relies on stimuli that are perceived (consciously) but processed in ways that influence later responses.
  • Example: Contextual priming with music and consumer behavior
    • Shoppers exposed to French or German music reported higher wine purchases when the music matched the country of origin of the wine.
  • Elderly stereotype priming experiment:
    • Participants completed a language task with word lists containing elderly-associated terms (old, bingo, walking stick, Florida) vs. a control task with non-elderly words.
    • After finishing, participants were secretly timed to walk to the nearest elevator. Those primed with elderly-associated words walked more slowly.
  • Intellectual performance priming:
    • Participants asked 42 general knowledge questions (Trivial Pursuit style).
    • Control (no prime) ~50% correct; primed with the intelligent professor stereotype achieved ~60% correct; primed with the hooligan stereotype performed at ~40% correct.
  • Replicability concerns:
    • Many priming effects have faced replication difficulties, so conclusions about their robustness should be cautious.
  • Overall takeaway: The brain can process information outside full conscious awareness and influence thoughts and behavior in nuanced ways, but not all priming effects are reliably replicable or large in magnitude.

Pheromones, Smell, and Human Mate Selection

  • Relationship between scents and attraction: Scent can influence attraction and sexual interest, sometimes consciously and other times unconsciously.
  • Pheromones and mating signals:
    • Pheromones are chemicals that convey information about reproductive status and influence sexual and social behavior.
    • In animals, pheromones are processed via the vomeronasal organ (VNO). Removal or damage to the VNO dramatically reduces pheromone-driven behaviors, underscoring the importance of pheromones and olfactory processing.
  • Humans and pheromones:
    • Humans may possess a VNO as well, and pheromones are thought to originate mainly from sweat glands in the armpits and pubic region.
    • Synthetic pheromones are commercially manufactured and marketed, though evidence remains debated.
  • Historical support and controversy:
    • Martha McClintock (1971) observed menstrual synchrony among women living together in close quarters, suggesting pheromonal influence; later studies using sweat applications to the upper lip showed increased synchrony, though replication attempts and methodological critiques have raised questions about robustness.
    • Menstrual synchrony: The concept relies on the assumption that cycle onset windows align across individuals. If the average cycle is 28 days, the maximum possible out-of-phase difference is 14 days; the typical average separation is about 7 days. Given a 5-day menstruation window, considerable overlap is common, which could be mistaken for synchrony by casual observation.
  • Critical considerations:
    • Many replications fail to reproduce strong synchrony effects; methodological and statistical concerns have been raised about early studies.
    • Despite questions about the exact mechanism or existence in humans, the idea persists culturally due to intuitive observations and anecdotal reports.
  • Human pheromones and behavior:
    • Placebo-controlled studies: Men and women wore synthetic pheromones or a placebo for several weeks; participants who wore pheromones reported higher sexual activity.
    • Pheromones appear to influence mate choice and sexual behavior in various ways, potentially aligning with theories of unconscious cues for healthier offspring via diverse MHC genes.
  • Pheromone preferences and MHC genetics:
    • A t-shirt study: Wearer’s shirt is sniffed by others who rate its scent; researchers compare the MHC (major histocompatibility complex) gene similarity between wearer and sniffer.
    • Result: The more different the MHC genes between the two individuals, the more positively the sniffer rates the shirt’s scent, suggesting a preference for genetically dissimilar partners to promote healthier offspring.
  • Evolutionary interpretation:
    • Pheromones may provide unconscious cues about potential mates’ genetic compatibility, contributing to mate selection beyond conscious awareness.
  • Current status and public interest:
    • Pheromone research remains controversial and partly speculative; some researchers explore “pheromone parties” and other social phenomena, but robust evidence in humans is not definitive.
  • Important caveats:
    • Effects are often unconscious and context-dependent; even if pheromones have effects, they are not guaranteed or universal across individuals.
    • If pheromones do exert real influence, their impact on behavior could be subtler and more situational than media portrayals suggest.

Menstrual Synchrony: Evidence, Replication, and Interpretation

  • Original claim: Synchrony observed in close-contact groups of women (McClintock, 1971) suggested pheromonal effects on menstrual timing.
  • Experimental follow-ups: Application of sweat to participants’ upper lips over months showed increased synchrony among participants receiving sweat.
  • Critiques and replication issues:
    • Later studies failed to consistently replicate synchrony effects; concerns raised about methodology, selection bias, and statistical analysis.
    • The observed synchrony could be explained by random chance or common environmental factors rather than pheromonal effects.
  • Theoretical and practical implications:
    • If true, pheromones could subtly influence reproductive biology and social dynamics.
    • In practice, the robustness of the effect is debated, and many psychologists recommend cautious interpretation.

Summary of Implications and Critical Takeaways

  • Inattentional blindness demonstrates limits of attention: even salient objects can be missed when attention is tightly focused on a task, particularly under high perceptual load; meaningfulness can modulate failures to notice.
  • Unconscious processing (mere exposure, subliminal processing, priming) can shape attitudes and expectations without conscious awareness, but empirical robustness varies; many effects depend on motivational states, context, and replication success.
  • Subliminal messaging as a tool for altering behavior remains controversial and not reliably demonstrated to produce real-world behavioral change; meaningful engagement with the stimuli and participant motivational state are crucial.
  • Priming can influence perception and behavior, but replication challenges warrant skepticism about the universality and strength of effects.
  • Pheromones and unconscious cues in humans may influence attraction and mate selection, but human pheromone research is complex, with findings that are intriguing but not conclusive; the potential for unconscious cues to affect behavior exists, yet the magnitude and consistency of effects remain debated.
  • Across topics, researchers emphasize the distinction between perceptual processing (what we sense) and conscious awareness, as well as the difference between attitudes or intentions and actual behavior.
  • Practical considerations: avoid oversimplified pop psychology conclusions; emphasize the importance of replication, methodological rigor, and context when interpreting unconscious processing research.

Connections to Foundational Principles and Real-World Relevance

  • Attention and consciousness: These discussions highlight how attention shapes what we notice and how consciousness interacts with automatic processes. The same brain systems that filter information for action can also condition attitudes and preferences outside awareness.
  • Learning and memory: Mere exposure, priming, and attitude formation illustrate how repeated exposure and semantic cues contribute to learning and decision-making without explicit memorization.
  • Evolutionary psychology: Pheromones and mate selection theories integrate biology, chemistry, and social behavior to explain how unconscious cues might influence reproductive success and genetic diversity.
  • Ethics and public communication: The discourse on subliminal messaging and advertising raises ethical questions about manipulation and consent in consumer behavior and media.
  • Replicability as a scientific baseline: Across these topics, replication success (or failure) shapes how confidently we can apply findings to policy, therapy, or everyday understanding.

Key Formulas and Numerical References (LaTeX)

  • Population and effect sizes mentioned:
    • Inattentional blindness prevalence reference: about 30\% of people or experiences depending on context (text implies variability).
    • Reese's Pieces impact: 65\% increase in sales after the E.T. release.
    • Transformers impact: 10\% increase in yellow Camaro sales.
    • Subliminal Lipton tea study: increased intention to drink among thirsty participants only (no direct behavior measure provided).
    • Priming performance differences (intelligence primes): control approx. 50\% correct; professor-prime approx. 60\%; hooligan-prime approx. 40\%.
    • General priming and perception effects are discussed without fixed numerical values in some cases; emphasis on replication concerns rather than fixed effect sizes.
  • Conceptual relationships:
    • Negative correlation between MHC similarity and attraction to shirt scent: more dissimilar MHC genes → higher attraction to scent; expressed as a negative association: r < 0 (conceptual, not a specific value).
    • Cycle timing guidance (menstrual synchrony rationale): if average cycle length is 28\text{ days}, maximum phase difference is 14\text{ days}; typical average offset is about 7\text{ days}; menstruation duration ≈ 5\text{ days}.

Additional Resources Mentioned

  • Video example of T-shirt pheromone studies available in the course’s week five module resources.
  • Consider reviewing the differences between subliminal perception and subliminal persuasion and the methodological standards used to test these ideas.

Quick Reference Takeaways

  • Inattentional blindness shows attention can blind us to obvious things when focused elsewhere; meaningful stimuli can modulate detection.
  • Mere exposure increases liking; attitudes can form or shift with exposure even without conscious awareness; real-world effects exist (ads, product placement) but depend on context and conscious processing.
  • Subliminal messaging can influence attitudes in specific motivationally states (e.g., thirst) but does not reliably drive behavior; beware conflating intention with action.
  • Priming demonstrates automatic cueing effects but is subject to replication concerns; not all priming results are robust.
  • Pheromones may unconsciously influence attraction and mating behaviors in humans; evidence is intriguing but not conclusive; menstrual synchrony findings are debated.
  • Across topics, the line between conscious processing and unconscious influence is nuanced, highlighting the importance of rigorous experimentation and cautious interpretation in psychology.