The digital shelf has a visibility problem.

Or at least, that’s what most brand teams think.

When a hero image attracts attention, generates clicks or performs well in visual attention testing, it is often assumed to be successful. The thinking goes something like this:

“If shoppers notice the image, the job is done.”

But that assumption overlooks a critical distinction.

Visibility is not glance readability.

A product image can be highly visible and still fail to communicate critical information shoppers need to make a purchase decision.

And in today’s mobile-first shopping environment, that difference matters more than ever.

The Difference Between Visibility and Glance Readability

Visibility answers one question:

Did the shopper notice the image?

Glance readability answers a different question:

Can the shopper successfully read and understand the critical text within the image at-a-glance?

These are not the same thing.

A visually striking hero image may attract attention because of its colours, contrast, packaging design or visual prominence. But if the product type, variant or size cannot be read quickly on a mobile device, the image may fail to communicate the information shoppers are actively looking for.

It’s like shouting at someone in a language they don’t understand. They look at you quizzically and walk away.

This distinction is becoming increasingly important as brands invest in hero image optimisation, digital shelf performance and AI-powered content testing.

Why Attention Alone Doesn’t Drive Conversion

For many years, digital commerce teams focused heavily on visibility metrics.

Common measures included:

• Impressions
• Click-through rates
• Attention scores
• Visual saliency analysis
• Heatmaps

These metrics help determine whether a visual asset captures attention.

What they do not reveal is whether shoppers can actually understand the information presented within that image.

A hero image may receive high attention scores while still performing poorly in terms of content comprehension.

This is where glance readability becomes essential.

According to the Neem’s glance readability test featuring the Cambridge Contrast And Size Tests (CamCAST) developed by Sam Waller, the objective is not simply to attract attention. The objective is to ensure critical information can be successfully read within a fraction of a second under realistic mobile viewing conditions.

The Mobile Commerce Reality

Most shoppers are no longer browsing product pages on large desktop monitors.

They are scrolling rapidly through product listings on smartphones.

Within these environments, hero images are frequently displayed as thumbnails.

The amount of information that can be communicated effectively becomes significantly constrained.

What appears perfectly clear during a desktop design review can become difficult or impossible to read when displayed at mobile thumbnail size.

This creates a challenge for brand teams.

Many assets are approved based on how they look on large screens rather than how they perform on the digital shelf.

As a result, product visibility may be high while glance readability remains low.

The Four Questions Every Hero Image Must Answer aka the 4W’s

When shoppers scan product listings, they are typically trying to answer a small set of practical questions.

These questions can be summarised as the “4Ws”:

#1. What Brand Is It?

Brand recognition remains one of the strongest drivers of shopper confidence.

If shoppers cannot quickly identify the brand, they may move on to a competitor that is easier to recognise.

#2. What Product Type Is It?

• Is it a facial serum?
• A moisturiser?
• A shampoo?
• A supplement?

Shoppers should not need to zoom in or read the product title to determine what the product actually is.

#3. What Variant Is It?

Different variants often solve different consumer needs.

The ability to quickly identify the correct formulation, flavour, scent or functional benefit is critical to shopper recognition.

#4. What Size Is It?

Pack size influences value perception, price comparison and purchase intent.

If shoppers cannot easily identify the quantity or volume, comparison becomes more difficult.

A hero image that fails to communicate these four elements at-a-glance may create friction during the purchase journey.

Why Product Titles Cannot Be Expected to Do the Work

A common assumption among brand teams is that shoppers will simply read the product title if they need more information.

However, mobile shopping behaviour often tells a different story.

Shoppers typically scan visual content first.

The hero image is often the most prominent and immediately accessible source of information within search results, category pages and marketplace listings.

If critical information cannot be obtained from the image itself, many shoppers may never invest the effort required to investigate further.

This is why hero image optimisation has become such an important component of digital shelf strategy.

The objective is not merely to display the product.

The objective is to communicate the product.

What Is Glance Readability?

Glance readability measures whether critical text within an image can be successfully read and understood at-a-glance.

Unlike traditional readability scoring systems, which evaluate the reading level required to understand paragraphs of text, glance readability focuses on short pieces of information presented within visual assets.

Examples include:

• Product names
• Product types
• Variant descriptors
• Size information
• Key benefits
• Promotional messages

The challenge is not whether shoppers could eventually read this information if they studied the image carefully.

The challenge is whether they can read it quickly during real-world shopping behaviour.

Measuring Glance Readability with Potential Glance Inclusion Percentage

One of the most important developments in this area is the introduction of Potential Glance Inclusion Percentage (PGIP).

PGIP estimates the percentage of the population likely to be able to successfully read text at-a-glance under defined viewing conditions.

The prediction is based on factors including:

• Character size
• APCA contrast difference
• Font weight / stroke width
• Uppercase characters
• Lowercase characters
• Numerals

This allows brands to move beyond subjective opinions and evaluate visual communication using objective, evidence-based measurements.

Rather than asking:

“Does this look readable?”

Teams can ask:

“What percentage of shoppers are likely to be able to read this information at-a-glance?”

The Science Behind Glance Readability

Glance readability assessment is supported by the Cambridge Contrast And Size Tests (CamCAST), developed by Dr Sam Waller.

CamCAST investigated how people perform when reading common words displayed for a glance duration of approximately 300 milliseconds.

The research explored variables including:

• Text size
• Contrast levels
• Font weight
• Uppercase text
• Lowercase text
• Numerical content

This experimental data provides a scientific foundation for predicting glance readability performance within ecommerce imagery.

It also helps explain why some hero images perform significantly better than others despite appearing visually similar during creative reviews.

Why Glance Readability Influences Digital Shelf Performance

Digital shelf performance depends on more than visibility.

A product that is noticed but not understood faces a significant disadvantage.

Glance readability can support:

# Faster Product Identification

Shoppers can quickly determine whether a product is relevant to their needs.

# Improved Shopper Recognition

Products become easier to distinguish from competing alternatives.

# Reduced Cognitive Effort

Less effort is required to interpret critical information.

# Better Content Comprehension

Key messages can be understood more quickly and accurately.

# Stronger Hero Image Performance

Important information remains accessible even at mobile thumbnail sizes.

Collectively, these factors contribute to a more effective shopping experience.

The Future of Hero Image Optimisation

The digital shelf is becoming increasingly competitive.

As brands produce more content and product ranges continue to expand, the ability to communicate clearly within limited screen space will become a defining advantage.

This is why glance readability is emerging as a critical performance indicator for digital commerce teams.

The question is no longer:

“Can shoppers see the image?”

The question is:

“Can shoppers read and understand what matters within a fraction of a second?”

Because visibility creates an opportunity.

Glance readability determines whether that opportunity is converted into understanding.

And understanding is what ultimately supports product selection.